Wren

The most beautiful way to compose and send a tweet on your Mac.
“Wren for Twitter is nearly perfect” – 52 Tiger
“So I closed TweetDeck, fired up Wren and went back to work.” – TNW
”One, it definitely reduces distraction.

Secondly, it also increases your tweet quality.” – Chris Bowler
“Wren has been beautifully designed” – MacStories
★★★★★ Featured by Apple in “New and Noteworthy” and “Staff Favorites”.
Features include:
☆ Awesome support for multiple accounts
☆ Post tweets with pictures using Twitter's image service
☆ Schedule tweets for later using Buffer
☆ Save drafts for later tweeting
☆ Keyboard shortcuts for everything
☆ Option to hide Dock icon
☆ Use your favorite link shortening service
☆ Username autocomplete
☆ Global keyboard shortcut for showing and hiding the app
☆ Full-screen mode in Lion
☆ See your last tweet so you know what you said last and how long ago you said it