Here's one for the iBro demographic I didn't even know existed: the iBottleopener. It's an iPhone case that's also — wa-a-a-ait for it — a bottle opener. If there's one thing I want my iPhone near, it's the opening of a bottle where sticky beer pours out.
By all appearances it's your usual rubber bumper case with cut-outs in all the right places so it won't block any ports or so on. Right now you can get one for $20 for an iPhone 3G or 3GS, and supposedly there's an iPhone 4 model on the way, too. (iPhone 4s and bars -- always a great combo!)