Gwibber - Gwibber is an open source microblogging client for GNOME developed with Python and GTK.
Tweedle App - Notion is nice but sometimes all you need is an app like Tweedle.
TweetDeck - TweetDeck is your personal browser for staying in touch with what’s happening now.
Plume - App for writing documents, scripts, books and more.
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.
Flamingo for Twitter - Flamingo for Twitter is a bright and colorful Twitter client that comes with a simple interface.