I've been using unRarX a lot lately and I ran into some problems when opening multiple rar files at the same time... Instead of sitting around unarchiving TV episodes one by one, I decided to spend a few hours writing an app to Do It for me. rawr! is based on rarlab's os x command line utility. It's pretty bare-Bones (not setup to support password protected archives yet), but it will let you open one or more files from the finder and queue them Up for unarchiving.
For the future I'm planning on implementing password support and allowing the queue to be modified (remove items, change order).