Twitter Search Engines 

• Resonancers.com - New! See which users get their tweets on Twitter’s home page the most. The best way to find the most influential people on Twitter  whether famous or not. @resonancers
• LocaFollow - A Tool For Searching and Following Other Twitterers - A Twitter search engine that enables you to locate and follow Twitter users by searching in their Bio and Location fields.
• Listiti - Google Alerts for Twitter Lists - Monitor Twitter Lists of your choice for keywords and receive free email alerts 
• GeoFollow: Search For Twitter Followers - Geo (location based) twitter user search. (Add youself to the directory by sending @geofollow YOUR CITY, YOUR STATE YOUR ZIP #tag1 #tag2 #tag3. EG: @geofollow Walnut Creek, CA 94596 #directory #geek #people
• TwitRadar.com is a realtime visual Twitter monitoring tool. Search by topics, tags or usernames and build your own social media monitor into live intuitive infographics.
• Heapr.com Heapr.com shows Google and Twitter results side by side in a very clean and super fast interface. THERE ARE NO ADVERTISEMENTS WHATSOEVER. Enjoy!
• Utwitbook Utwitbook is a place to find top twitter people who share your interests, location, url and even design colors.
• Advanced User Search New!- Search from name, location, and biodata with given keywords. Google powered.
• Twicsy - Twitter picture search engine that indexes tweets, shows most popular pictures of the past hour, day, week, and shows related pics.
• Tweeple411 ~ World's first Tweeple driven Directory. Find people with similar interests to follow or add your Twitter or FriendFeed page. Power to the Tweeple!
• TweetFeel - Twitter Search with Feelings.
• Twoquick - Super-simple search of Google and Twitter displayed side-by-side. Look up stuff on Google and see what people are saying about it on Twitter.
• twittermap.de is a Googlemaps mashup which lets you search something on a map or shows you People in a proximity of a city. It also displays other Regions if you wish on other TLD's like .tv (Worlwide), .us, .com.mx, .eu, .es, .fr
• Tweetsmap is a User-input Based Google Mashup which allows you to search Twitter Users near you or finding the Users adress by typing the Username
• Twazzup - Twazzup organizes search results so you can quickly turn the buzz on twitter into useful information. Search results include related keywords and hashtags, trendmakers along with popular tweets, twittpics and links.
• Twifish - Extends twitter search and also searches for synonym words and phrases in twitter.
• Twimme NEW – Find out what giveaways, contests, coupons, discounts, freebies and more are being tweeted right now by twitter users.
• tweetzi - Twitter Search & Trends - A search service for finding and teasing out useful info from the 'Twittersphere'.
• Tweeple Pages – A user powered directory of Twitter users organized by their interests.
• MicroPlaza – Tribal Search, search the hot links shared on twitter and discover the trending topics.
• allyve.com - Only available in German. Create your personalized startpage and combine it with lots of other personalized widgets like myspace, facebook and other stuff from across the web to your page.
• FAROO - A Peer-to-peer Web Search Engine, that integrates Twitter search to discover discussions and people related to the query.
• FreeSearch - Find your friends on the web. Simply "follow" freesearch, tweet "@freesearch pete cashmore" or any other name, then wait a minute for the results!
• Green Tweets - Tracks tweets about green & environmental topics based on semantic natural language analysis rather than keyword
• Navgle.com - Mashup of Twitter Search with Google Search Services to display search results as Universal Search results clustered by source type (Twitter, Web, News, Blog, Q&A, Encyclopedia, etc.)
• OneRiot Twitter Search - OneRiot's Twitter search results, for any query, reveal the relevant web pages that are currently being discussed within the Twitter community.
• TweetJobSearch - Search jobs posted on Twitter
• TweetFind.com - Twitter Directory to Find Twitter Accounts and Add Your Twitter for FREE.
• Tweet on the Street - A Twitter-based rumor mill. Search for the latest buzz on technology, celebrities, politics, sports, and more.
• Tweet Scan - Search public Twitter posts in real-time from the page or using Firefox's search box. Find replies, track keywords, and sign up for daily/weekly email alerts.
• Searching for Interesting Topics on Twitter - Search for comments and users that interst you. Great for finding people to connect with your personal interest.
• Terraminds micro search - Search entire public timeline in realtime, fast & responsive! New: Twitter search API
• Twellow.com: A People Directory - A directory of Twitter users categorized into hundreds of fields of interest. Allows user to login and categorize themselves.

• LocaFollow - A Tool For Searching and Following Other Twitterers - A Twitter search engine that enables you to locate and follow Twitter users by searching in their Bio and Location fields.

• TwiST -- Twitter Search Tool, an easy-to-use interface to Twitter Search
• TwitterTroll.com - Real-time Twitter search engine. Search through 1000s of indexed tweets everyday and find new friends.
• Twitterment beta Combines Twitter apps with a search engine and graphing tools
• TwitterJobSearch - The first semantic search engine for twitter. Finds all the jobs posted on twitter.
• TwitterSearch -- Full text searching for the recent Twitter zeitgeist, complete with toy dude-heads. A must! Also maps posts via Twittermap!
• Top News Trends - Top News Trends combines google trends data with twitter search.
• Twitter.FM -- Simple but multilingual full text search engine for Twitter, supports CJK, Arabec, etc. Country specified search is also provided in US.Twitter.FM, CA.Twitter.FM, UK,CN,JP,ES,TW,...more!
• Twitterverse - a search and visualization project which mines and archives the public timeline of Twitter and provides a visualization of the most commonly used words in a given time period. Search Twitter by keyword.
• TwitDir - A Twitter directory, no more. You are looking for someone, something? Just type a few words in the search engine. Enjoy!
• MobiFeedLive.com Receive Keyword Based Email Alerts so you can see who is saying what about you... Also has Search, Link Metrics, and Trend Analysis...
• Summize Twitter Search - Realtime twitter search with language restriction and threading built right in. Free API included.
• Twitigg - See tweeted links Digg style.
• Twubble -- Recommends new people to follow based upon your existing follows
• WhoShouldiFollow? -- Recommends interesting people to follow based on your network, and supports searching for a location and adjusting for popularity.
• picobuzz - Shows popular buzz words from the public timeline and who's sayin' them!
• Intwition - Tracks what people are linking to and discussing on Twitter. Let's you lookup and find tweets about any site. Provides an RSS feed to track tweets about any site as well.
• Twitter Blacklist - Collects IDs of Twitter "spammer" accounts, those that follow thousands of users at random, in hopes they'll reciprocate and open themselves up to direct-message access. Site offers an API, a Javascript bookmarklet for quick checking wither a given Twitter ID is a flagged spammer, and links to related resources such as a Greasemonkey script (for Firefox+Greasemonkey) that also auto-checks users against the blacklist.
• twitter search -Twitter Search engine find through 1000s of indexed pages kuber twitter and pdf twitter search
• FuelFrog - Use Twitter to keep a log of your fuel and mileage. Compare your mileage with others in your area, or with the same car.
• TwitFuel - Submit and share local gas prices in your city. Find up-to-date prices submitted by your fellow tweeples and never pay too much for gas again!
• TweetBeep.com - Twitter Email Alerts - Like Google alerts, but for Twitter! Save keyword searches and link/domain searches and be alerted by email when someone on Twitter mentions it! Free service, by @mdjensen
• Tweetag - Browse the twittosphere with nested tagclouds and never miss any raising trend related to your favorite topics
• FutureTweets - a free service that lets you schedule your Twitter messages. Send it at a specific time in the future or send a reoccuring Tweet daily, weekly, monthly or yearly! Handy if you're in need of an alibi.
• Twitturls Popular Twitter Links Tweeted err Twittered err Twhatever - Links / Pictures / Video - What's hot on Twitter
• TwiSpot.com – TwiSpot is a Topic-Based Social Exploration Tool based on Twitter. Stay updated and explore interesting new topics with theHottest Tweets all in one spot.
• Twithelp.me - Help people in the Twitter community find answers to things they want to know about. Search Twithelp.me for topics, then reply direct to anyone who you can help. You can set up RSS feeds too to be alerted of future Twithelps. If you want help, just include#twithelp in a tweet. (...think of it as Yahoo Answers for Twitter.)
• PopularTweets.com - Browse the current top 10 most popular tweets, re-tweets, friends and followers on Twitter right now.
• TweepSearch - Search Twitter bios, currently over 1 million indexed. Also provides the ability to search the bios of only those people following you.
• TweeterLookup – The easiest way to lookup mutiple Twitter usernames at once from a list of email addresses, without having to input the list into your webmail accounts.
• Android software tweets - Watch realtime tweets about Google Android phone(with database with older tweets)
• BackTweets - Search for links on Twitter (even if they've been shortened)
• TwitterPray - A real time snapshot of what people are praying about on Twitter and what people are requesting for prayer.  Trending, history, and request tracking (among other features) are slated to be added in the coming weeks.
• Tweeple of India - A searchable directory of twitter users from India
• tweetactive - Search tweets & get real time stream.
• TweetRSVP - Tweets that include a question, request for information or offers [new feature] are pulled and available on TweetRSVP in real-time, or through a searchable database or via email.  Visitors can reply or RSVP to a tweet directly from the site through twitter.com or by copy and paste if using a desktop client.
• http://www.feeltiptop.com  - TipTop is a semantic search engine that transforms how you can search & view data from Twitter.  Visit it to see what it is and what it is not.
• Twit4 Directory  - A twitter directory that helps users find companies that use twitter. Twitter accounts are organized by companies, schools, brands, and organizations. Find twitter companies easily at Twit4.com.
• Twitter Job Finder - Search jobs recently tweeted by job type & location.