Tweeterized

Create a dynamic Twitter signature that you can use on forums or social networks.

TweetStalk Follow people on Twitter without them knowing you are. Pretty cool tool :).

Twitbin Keep up with your Twitter conversations from the browser’s sidebar.

FriendBar Combine your favorite browser with Twitter for maximum tweeting experience.

TwitterLine Displays tweets in a toolbar in Firefox. Also you can post updates to your account.

BubbleTweet - Create a 30 sec video in a floating bubble video player on your Twitter page. This is a very cool and innovative Twitter application. Greet your friends and new followers in a short video :).

Twitemerature - Find out how hot you are! 

Mr. Tweet - Get recommendations of who you should follow.

TweetChat - Create rooms in Twitter to chat about everything you want.

TweetBeep - Find out who talks about you or your website!

Twitter Analyzer is one of the most extensive Twitter applications ever… basically, its a tool for Twitter users to analyze themselves or their friends, but Twitter Analyzer takes the statistics data to a much higher level… (it is called by some Twitter users the "Google Analytics for Twitter users") and rightly so, TwitterAnalyzer features more then 50 statistics measures displayed in 3D graphs and World Maps enabling surgical precision tuning of your twitter stream… you would discover many things about your or your friends Twitter presence… you can even share your statistics with your friends.

Twitter Top Twenty is a top 20 list of everything on twitter including stats, users, and trends.

Tweet Buzzer lets you track the brand buzz on Twitter. You can see the top tweeted brands in a 24 hour, 7-day, or 30-day period. You can also track your favorite brand, see the percentage change over time in tweets and impressions, and submit a brand to be tracked.

Klout Discover how influential you are on Twitter. See who influences your friends and measure the impact of your content.