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