A simple active wallpaper that gives an at-a-glance indication of the signal strength. Signal bars on the phone are notoriously inaccurate and vary between phones.
This wallpaper will let you see easily the current signal strength. Red indicates a poor signal and green a good one. With orange or yellow, you're probably okay but be ready for the call to break up!
Very useful when the phone is in the car cradle.
Only tested with GSM only at the moment. A CDMA update will be coming soon.

Screenshots: