Seems you can't open a newspaper or magazine right now without seeing an ad for iPhone applications. Most of these are tedious time-wasters for bored stockbrokers. Others, like iBeer (a visual display of a pint of lager that you can 'pour' down your throat) are just pointless.

But Tap Tap Revenge 2, which you can download here, is genuinely addictive, primarily because it's just like playing 'Guitar Hero' on your iPhone, and comes with free tracks by bands including Death Cab For Cutie and The Crystal Method. See the game in action here.

It's one further stage in a process that has seen developers and nerds increasingly use their iPhones as musical instruments. Who knew, for example, that you could play MGMT's 'Kids' using only iPhones and iPod Touches?