I couldn't get any of the existing bluetooth toggle widgets to work on Droid (Android 2.0). So this one does.
1.1: Fixed some force close issues. Also added an unknown state icon when the bluetooth subsystem is unavailable.
Once installed: long press on your home screen, select "Widgets" then "Droid Bluetooth Toggle"
Wood, Glass, or Metal, but in the future I might add other things for you to knock on.
If you have other ideas please post them in reviews... I will try and read them and update it!
1.1.1 (1/13/09): Added glass and metal. Also better wood noise.
1.0.1 (1/12/09): Fixed a crash issue when you knock really fast.