Janetter - Janetter is a Twitter client application. Faster, smarter, and more powerful.
Maker Swipe File - 100+ high-performing Tweets to help you grow your audience
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.
Narrow - Narrow helps you build a targeted audience and increase your influence on twitter.
YoruFukurou - YoruFukurou (NightOwl) is a Twitter client for Mac OS X, designed for Twitter addicts.
TweetPilot - Grow a relevant & responsive following on Twitter