Has your iPhone been dropping calls on you? Not giving you the number of bars you were hoping for when you picked it up? Well, don't return it! No, you don't want to do that. Instead, get an ugly case with a cell phone booster on it, ruining the clean design of the phone but giving you a stronger signal.
The Griffin ClearBoost is an ugly-as-sin case for the iPhone that has a protruding stub of an antenna that's supposed to help get rid of dropped calls and make your phone experience better. Personally, I'd rather just move to an area with better coverage, but my priorities are pretty out of whack, so your mileage may vary.