Apps, Widgets and Plugins – Windows
Pwytter – Cross platform Python Twitter client with Asian character support.
Teletwitter – Experimental open source client.
TwitBox – View and submit tweets, see replies and direct messages, delete your own tweets, and multiple account support.
Twitterlicious – Update Twitter status, easily check replies and direct messages.
Twitteroo – Client with rurl URL shortening, clickable links and tweets, customization, and both public and friend timelines.
Chirrup – Twitter client with extensive Japanese language support.
TwittIt – Extremely compact and simple app for submitting tweets.
MadTwitter – A reincarnation of Twitterrific, except on Windows.
Twitter CLI – Post tweets via the command line.
What’s Up? – Gadget that allows you to see latest tweets from your friends.
Twadget – Simple gadget that lets you view and submit tweets right from Vista’s Sidebar.
KipFolio Widget – Simple Twitter widget for KipFolio.
Twitter-Sync for Yahoo – Syncs Twitter status with Yahoo Messenger status.
TwitterYM – Simple Yahoo Messenger status updater.
Twessenger – Updates Live Messenger status to reflect latest tweet.
Twit4Live – Set status message as latest tweet, send tweets from within Live Messenger, and send tweets to contacts.
Apps, Widgets and Plugins – Mac
Twitterrific – A compact client that publishes tweets, shows unread tweets, has easy access to profile pages, shows either public or friend timeline, and more.
TwitterPost – Basic client that submits tweets, shows your current iTunes track in your feed, and more.
Twitgit – Read your friend’s tweets and submit your own, right in Dashboard.
TweetAhead – Schedule tweets to be posted ahead of time with a simple Dashboard widget.
Twitterlex – Dashboard widget that shows your friend’s latest tweets as well as allows you to submit tweets.
Twidget – Update your Twitter status within Dashboard.
TikiTwit – Match your iChat status to your last tweet.
Apps, Widgets and Plugins – Linux
BLT – Perl script that lets you see what your friends are doing right from the Terminal.
Twitter for Vim – Publish tweets right within Vim.
ZenTwitter – A GUI frontend for Twitter using zenity and curl.
Twitux – Twitter client for the GNOME desktop.
gTwitter – GTK+ based app inspired by Twitterrific.
Twitter.el – Publish tweets while in Emacs.
Twitbar – Post tweets from the GNOME deskbar.
Twit.el – Another utility that allows publishing of tweets within Emacs.
Cross-platform Apps, Widgets and Plugins
Tweetr – Submit tweets, upload files, urltea built in, delete messages.
Spaz – Cross-platform client built with AIR.
Tweeter – Java based client with customizable UI.
Twinja – AIR based client which allows you to follow users on the fly.
Twitterverse – Search through archived public timelines and tweets.
Twittersearch – Search Twitter and tweets by word.
Terraminds – Search for specific users or tweets.
TwitDir – Allows user to search for users by name, location, or username.
TwitBin – Send and view tweets right within Firefox
TwittyTunes – A FoxyTunes addon that posts what you’re currently listening to Twitter.
Shareaholic – Share links and webpages via Twitter right within Firefox.
Search Plugin – Tweet right from the Firefox search box.
Tweetbar – Put Twitter on your Firefox sidebar.
Twippera – Twitter widget for Opera that can send and view tweets.
TwitterFox – Compact Firefox extension that can publish and view tweets.
iTweet – A mobile Twitter site designed for the iPhone.
iTwit – Mobile version of Twitter made for the iPhone.
Tweeter – Twitter on your mobile phone while avoiding text message charges.
Jargong – Browse Flickr, do some social networking, but most importantly, check and publish tweets.
WildSets – Extensve Twitter app for mobile phones.
TwitterBerry – Twitter built for various BlackBerry devices. Update and view timelines with ease.
jTwitter – View timelines, enter updates, and more, all on your mobile phone.
TreoTwit – Easily check and update your Twitter right from your Treo.
Twittervision – See where in the world people are submitting tweets from, real time.
TwitThis – Allow visitors to your site to easily share a page or post via Twitter.
MoniTwitter – Receive important updates about your site via Twitter.
TwitterNotes – Share private or public notes via Twitter.
RSS2Twitter – Share any RSS feed on Twitter, and have new RSS items automatically be tweeted.
TwitterBuzz – Find out what is being most linked to on Twitter.
Twitterholic – Shows the top users and accounts on Twitter.
Happy Tweeting! Follow me!