Tweetium - Tweetium is first and foremost designed to be quick and reliable.
TweetDeck - TweetDeck is your personal browser for staying in touch with what’s happening now.
HootSuite - Enhance your social media management with Hootsuite, the leading social media dashboard. Manage multiple networks and profiles and measure your campaign results.
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.
TweetDuck - Free & open source desktop client for TweetDeck
Seesmic - Seesmic was a suite of freeware web, mobile, and desktop applications which allowed users to simultaneously manage user accounts for multiple social networks, such as Facebook and Twitter.