The Gadget: Belkin's iPhone headphone adapter, which lets you use any set of headphones that don't normally fit into the iPhone's recessed headphone jack.
The verdict: Works exactly as advertised. Fits all headphones with no audible sound quality loss.
It's mf-ing gigantic. It's longer than the iPhone is wide, and can't really be used in tight pocket situations. But it does have a flexible center, which means you won't be able to break it easily.
The performance: Worked great on my car's tape adapter. No audible sound degradation when plugging a set of headphones into the iPhone and plugging through the Belkin adapter.
The price: $10.95
The recommendation: As the first and only headphone adapter for the iPhone out now, you've got no choice. You have to buy this if you want to use non-skinny headphones on the iPhone. The huge size doesn't matter in the car or at home, but sucks when you put it in your pocket.