I killed my first generation iPhone a few weeks ago, and was gifted a new 3G for Mother's Day -- yay me!
I just found the most awesome cover for it, I just have to share:
It's made by SwitchEasy, and is the CaspuleRebel model. The colors are fantastic -- I got the happy happy Cherry. I love that it has the silicone soft cover for grippiness, and the ridged plastic reinforcement for protection.