Photojojo's new Lens Dial is at once ace and awful.
Available on iPhone 4 and 4S, users are able to rotate between fisheye, telephoto and wide-angle lenses.
All very cool, but clearly it adds some serious chunkiness to your mob and weighs ten ounces (twice that of the iPhone). It does add flexibility though, allowing for a tripod add on for landscape or portrait scenes.
It's shipping in the US for $250. No word on the UK just yet.