Apologies if this is rather 'ipod married goat' but I've only recently updated my version of itunes and discovered genius. The idea is that you can click on any song in your library and it will SOMEHOW automatically generate a playlist of similar songs.

'Yeah, right' I think and at random click on Mogwai's Christmas Steps. Straight away I get a playlist of:

Godspeed!
Explosions in the sky
Mono
God is an astronaut
Slint
etc
Basically a fairly good 'old school post rock' playlist. HOW DOES IT DO THIS? It can't be anything as crude as the 'genre' tags, mostly they're laughably inaccurate.

On wikipedia it says it is all down to 'algorithms' but to me this is the same as saying 'sorcery'.