BetterTTV enhances Twitch with new features, bug fixes, and reduced clutter.
The multi-functional screenshot utility for OS X that doesn't suck
Nightbot is a chat bot for Twitch that can perfom a variety of moderating tasks specifically designed to create a more efficient and friendly environment for your community.
Watch Twitch on your television (with Chromecast)
Stream Twitch chat directly in Open Broadcaster Software or XSplit