Search Engines 

• SocialBro.com -  New!  Social Media CRM Dashboard. Analytics reports, Twitter list management, follow/unfollow tracking, powerfull followers search engine and more.
• TweetFind.com -New! Twitter Directory with Twitter Lists  - Search Twitter Lists, Businesses, Users, & Celebrities - Get More Twitter Followers @TweetFind
• FriendLynx - New! Find and Follow your Facebook friends on Twitter. Create Twitter Lists with your Facebook Friends.
• 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
• RetweetFollow - New! RetweetFollow lets you search by keywords in URLs tweeted and to easily follow the retweeters. You can also create lists, export the results, thank the RTs.
• 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
• Cloud Search - Search for your favorite topic through an intuitive visualization. Generates a tag cloud based on the popularity of related terms. Also returns twitpic results and the list of users.
• LocaFollow - A Tool For Searching and Following Local Twitterers - A Twitter search engine that enables you to locate and follow Twitter users by searching in their Bio and Location fields.
• inasectv.com - INASECTV is a one stop destination for Sports Discovery on the internet.  We combine elements of Social Media, Videos and News, then organize it for you.
• lmstfy.com - Let Me Search Twitter For You. A fun app that guides users towards searching twitter for realtime information.
• 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. Also a browser plugin can be downloaded so you can search from the top right of your browser.
• BrandSentiment.PeopleBrowsr - A sentiment tool that allows to track your brand's buzz, customers and competitors. BrandSentiment classifies Tweets as positive or negative. Export ready-to-print brand sentiment reports.
• HotList.PeopleBrowsr - HotList builds a live stream of Twitter posts for an industry, a group or an @name and analyzes the sentiment of each post and rates it as positive or negative. Monitor what are Twitter users saying about hot celebrities, TV Shows, travel destinations, airlines, Twitter Apps and much more. Interact with the stream by sending your tweets. See live trending and look at detailed profiles. As a business you can access to your Brand deep sentiment data, getting to know your customers feedback and seeing your sentiment evolution over time. Learn also about your competitors and what people are loving or hating about other brands in your field.
• My.PeopleBrowsr - My.PeopleBrowsr is a real-time search engine and data mine for you to look into the pulse of digital conversations and engage across multiple social networks simultaneously. With filtering, you can bubble up "memes and themes" that are important to you across any "Web 2.0" service. Manage multiple accounts and post to multiple networks at the same time. Choose your dashboard mode: Lite, Advanced or Business. My.PeopleBrowsr is web based, no download needed.
• News.PeopleBrowsr - Monitor trending topics over a time interval. Create and apply your own filter or select a keyword. Publish your news Tweets and share them within your network: become a news editor!
• Nsyght - Nsyght is a different kind of realtime social aggregator. Nsyght is able to not only aggregate a users own social information, but also information from their friends, even if they are not nsyght users. Instead of joining nsyght and being forced to spend time re-friending people they already follow, and having to rebuild their “communities” from scratch, nsyght does that for them via their existing social graph. nsyght also makes it easy to share news, posts, videos/photos, and discussions across networks. 
• Sbot - Search twitter right from your IM. Add sbot as your buddy & send t<space>search term & bot responds you with results. Ex: t @hnprashanth will return tweets containing @hnprashanth. Supported on gtalk, Yahoo! messenger & Windows Live Messenger.
• Search.PeopleBrowsr - Simple live search on multiple social networks. Search.PeopleBrowsr sorts tweets by authority, location and link to find out in a glance what the influencers are saying about subjects that are important to you or your brand. Bubble up "memes and themes" you are interested in. The live trending feature helps monitoring all the most popular keywords by time intervals and keeps you up to date with the latest hot topics.
• Utwitbook - Utwitbook is a place to find top twitter people who share your interests, location, url and even design colors.
• Feald - Feald is a search engine and Twitter media center with many useful twitter tools to increase your twitter followers amount, Feald takes your twittering to the next level. Search twitter with video suggestion tool, great tools list and much more.
• Tweetmondo - Search for local Twitter users. Find people in your country, city or even street in this fun new app.
• 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.
• 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.
• Advanced User Search - Search from name, location, and biodata with given keywords. Google powered.
• Tweeple Pages – A user powered directory of Twitter users organized by their interests.
• TwitMesh - Create groups, send invitations to your followers. Twitter IM to chat with your friends via Twitter. Streaming search fom twitter and more..
• More...