Gwibber - Gwibber is an open source microblogging client for GNOME developed with Python and GTK.
Oysttyer - Oysttyer is a console text-based command-line Twitter client and Perl platform, fork of...
TweetDeck - TweetDeck is your personal browser for staying in touch with what’s happening now.
Turpial - Turpial is a lightweight and beautiful microblogging client written in Python.
Tweetbot - Sync your timeline across your iPhone, iPad, and Mac. Mute tweets by user, hashtag, tweet source, or keywords (including regex). 3rd Party support for image, video, read later, and timeline sync services.
YoruFukurou - YoruFukurou (NightOwl) is a Twitter client for Mac OS X, designed for Twitter addicts.