Frets on Fire

Tip for those with kids, nephews, nieces or too much time on your hands:

Frets on Fire is an open source (free) version of a game very similar to Guitar Hero. You don't need a pseudo guitar like GH has; you can hold your computer keyboard upside down, assign function keys and "play" your keyboard. You're not learning to play the guitar, of course, with either GH or FoF, but you do get familiar with guitar parts in a way that you might not have been, so it does have a little bit of music education value. And you don't shoot anyone.