One benefit of the Droid is having a physical keyboard. And with that comes a Dpad which is great for games... the only problem is the Dpad is on the right hand side.
That's where the Game Gripper comes in. It is a soft plastic attachment that clips onto the keyboard and provides a left-hand Dpad and 8 face buttons. The buttons on the Game Gripper simply press the keyboard button below, so you'll still have to setup the proper keys in emulators... but it seems to work very well.
Check out the website for a demo video. It's only $15... I'm ordering one now! (I'll make a review when I get it.)