ilo - Premium Twitter analytics
Refined Twitter - A browser extension that improves the Twitter experience
Accountanalysis - A tool to evaluate Twitter accounts
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.
Tweetastic - Better Twitter analytics, scheduling and more
ClockTweets - Schedule, analyze, and stalk challengers on Twitter