Its not free, but I bought the Line 6 Guitar Port, and it was pretty good for what it was. I'm not a huge fan of "virtual" amps, or really plugging into the computer to play, but its a great way to get lots of variety in your sounds without breaking the bank. In the end though, a quality amp or processor is nicer just for the quick "plug & play" option. I find setting up the Guitar Port a bit of a pain sometimes, but that's just me.