Tools of the trade: Versione Karaoke

Versione Karaoke is an italian website which provides karaoke versions of songs; the most important and useful thing is that once you bought the (cheap) song you can customize it, picking only the tracks that you want:

So you can, for instance, mute the guitar parts and play along with the track. You can also change pitch and add a nice metronome sound. Neat, isn't it?