A Mac client for App.net.
Some wonderful features:
All of the basics: post, reply, star, repost. View followers, threads, hashtags, and more.
Unified Stream of posts and your mentions.
Notification Center support and an optional status item in your menu bar.
Full support for the MacBook Pro with Retina Display.
Swipe gestures and animations!
A few known issues:
Large following & followers lists don't always load all items.
User profile description measuring isn't quite right, some text can be obscured.