Shazam! is a really rather cunning system; dial 2580 on your mobile phone, hold it up to a loudspeaker, and a few seconds later it'll text you the name of the track being played. Remarkably, it works; here are brief notes on how.
Sadly, I've only used it about twice in the last year. Bloody clever, but I'm not sure how much use it is.
Wow! Oh, and costs 50p!