What is right now under your hand ???
Yes ! It's your keyboard !

And what can you do with your keyboard ?!

Right ! You can play guitar !

http://kempele.fi/~skyostil/uv/fretsonfire/

this is so much fun

here's a foretaste:
http://www.youtube.com/watch?v=t5rANYBQvF0

i just played that for two hours at my work

Saw it a few weeks ago Man, I was mad - I had that same idea last year in school, but I never had the skill to make it! But they pulled it off really well, better than I could've ever done it. I just wish there were more songs.

There already are:
http://frets.freenerd.org/?songs