This sounds to good to be true, but Liquipel claims that they can make your iPhone (or any other device) waterproof without a case, with a process that applies a patent pending waterproof coating on the iPhone to protect it from water or liquids.
Liquipel explains how it works:
Liquipel is a revolutionary process that applies a waterproof coating to your electronic device to protect them in the event of accidental exposure to liquids. It is not visible to the human eye, virtually undetectable and Liquipel will not compromise the look, feel, and performance of your electronics.
Liquipel penetrates the entire device as a whole, including all of the vital components inside and out to provide optimal protection against accidental contact with liquids.
As you may have guessed, you need to send your iPhone to Liquipel to get it waterproofed. Liquipel is currently offering this service for $59 with a 1 to 2 day turnaround time.
You can check out the video below to see their product in action and the second video also shows how it works: