Despite its huge library of games, the iPhone isn't really the best portable gaming machine. That's because its touchscreen does away with any buttons and the tactile feedback they provide, which makes gaming significantly harder.
But these Tactile+Plus stickers aim to fix that. Simply put them on your iPhone's screen where the touchscreen buttons are and all of the sudden you've got something to feel when you push down. How well they work isn't clear, but for $7.80 they seem worth a shot.