TweetDeck - TweetDeck is your personal browser for staying in touch with what’s happening now.
Twitterfall - Twitterfall is an excellent choice if you want something basic, free and without much branding.
Tweetdeckr - Tweetdeckr is an open source Tweetdeck replacement client.
TweetDuck - Free & open source desktop client for TweetDeck
Flightly - The must have mobile app for anyone advertising on Twitter.
HootSuite - Enhance your social media management with Hootsuite, the leading social media dashboard. Manage multiple networks and profiles and measure your campaign results.