Events / Groups / Organizations

• IsItBangus - Find the coolest bars, clubs, and events.  When people tweet <place> is bangus, this site puts it up on the map, grouping by the place.  Searching sorts by most recently cool stuff in the area.
• ConnectTweet - Groups and businesses are made up of many people, not faceless Twitter bots or a single person's voice. ConnectTweet facilitates your voices combining.
• Tinker - Tinker is a simple way to discover events people are chattering about on Twitter.
• Tweetizen - Discover tweets that matter to you. Create groups based on your interests and filter tweets that you want to read. You no longer will have to scan through thousands of tweets to find something useful. You can find groups on technology, jobs, gossip, news - think Digg.com, but for tweets.
• TweetLaw - An application specifically for legal professionals. Legal professionals who join TweetLaw can fill out an extended bio page as well as include themselves in up to 4 legal categories. You can then sort tweets by categories and user.
• TweetMind a fully featured desktop app supporting multiple color coded accounts, groups, automatic URL shortening, CoTags and much more.
• Tweetworks - With groups and threaded discussions, Tweetworks makes tweeting more useful by tuning out the noise and letting you participate in the conversations that interest you most.
• ComTweets - A service for enterprise workers on twitter. ComTweets makes it easy to discover other employees on twitter, follow their tweets and latest URLs they're talking about. Customers can also easily find out whether an account is authentic for the organization.
• Twit4 - Twit4 enables companies to organize twitter accounts relevant to their business all in one spot.
• TweetKnot - provides platform to share the short messages(140 chars) across people via public/private communities called Knots. Owner can order knot to follow multiple twitter users. Any twitter user can join a knot and get all updates.
• Twtvite -  is a simple event manager twitter app. Create an event, enter the location, date, time, your 140 chars description, and share it/ manage RSVPs. (by @twtapps)
• twtseat - twtseat is standardizing the way tweets are sent about events and provide ticket information to those who wish to also attend the events of their followers.
• UKTJPR - tracks the activity of UK journalists and PRs in real-time, making it easy to see what is happening in the UK technology industry. A tag cloud is generated to show trending topics, while columns categorise the feed into status updates, links or photos. Extra columns can be added to run custom searches of the feed. (by @justfdi and based on JournoTwit)