BulletTrain Express Keyboard Platform
Ubergizmo wrote a short review of the BulletTrain Express Keyboard Platform:
BulletTrain Express Adapter Turns Your Keyboard and Magic TrackPad Into a MBP Surface
Did you ever want your iMac to feel more like a MacBook Pro?
While this isn't a casemod to do that, you could still get the same keyboard and trackpad feel of the MacBook Pro with the BulletTrain Express.
This item is simply a large chunk of aluminum that allows you to fit your Apple Bluetooth Keyboard and Magic TrackPad into it, giving you the feel of typing on a MacBook Pro.
While it's nice to have a large chunk of aluminum on your desk, you do have to question whether it's worth your money to shell out $99 for something that doesn't really do anything.