F1 is a browser extension that allows you to share links in a fast and fun way. Share links from within the browser, from any webpage, using the same services you already know and love.

ThinkUp captures your posts, replies, retweets, friends, followers, and links on social networks like (but not limited to) Twitter and Facebook. ThinkUp stores this social data in a database you control, and makes it available to search, sort, filter, export, and visualize in useful ways.

ThinkUp is a free software project licensed under the GNU GPL, founded by Gina Trapani, sponsored by Expert Labs, used by the White House, and built by an enthusiastic community of contributors like you.

Ever seen a hashtag on Twitter, and wondered what it is all about? Now you can look it up, and cast your vote on the definitions. And if you don't like the definitions, or none exists, you can create your own in seconds.

Sideline is an Adobe® AIR™ desktop application built with the Yahoo! User Interface Library (YUI). It allows users to create and group custom queries by topics of interest. Sideline is an open source application released under the BSD license.

Add your Twitter backlog feed to your favorite calendar application and browse through your personal Twitter diary, making your Twitter history both fun and useful!

Syrinx is a fully customizable twitter client designed for Leopard (OS X 10.5+). Syrinx is built from two ideals: efficient workflow and customization.

twhirl is a desktop twitter client, based on the Adobe AIR platform.

Twistori filters Twitter posts around "I love", "I hate", "I think", "I believe", "I feel", "I wish".

quotably.com/popular is a look at what's being talked about on Twitter right now.

Post to Twitter from your Firefox address bar

Here’s how to get your blog (or any other RSS or Atom feed) twittering: