If you're into gaming on your Android device you'll know how annoying touch screen controls can be. Touch screen I've found only works with some types of games, such as Angry Birds. But if you like playing games like GTA 3, your thumbs can get in the way.
Gameklip is a very neat accessory made for some Android devices which lets you play games with a PS3 DualShock 3 controller. It hooks onto the controller, you connect the controller to your phone via Bluetooth, then just slot the phone in and you're away.
It only works with a select few Android devices though and that's because of compatibility issues. If you have a rooted Android device you can still get the thing working, but that's another procedure in itself.