MilkHub

dotwaffle showed me this game last night and it's brilliant. I can't seem to move both of my hands in the right patterns to go much beyond the easy settings but still great fun. It's a bit like guitar hero for the PS2, though you use your keyboard rather than a custom guitar.

Their website says:

Frets on Fire is a game of musical skill and fast fingers. The aim of the game is to play guitar with the keyboard as accurately as possible.

Have a look: Frets On Fire

You can also download more frets from Keyboards On Fire (the link is on the left of the Frets On Fire homepage).