The best free game available right now is Trackmania Nations Forever. Always been a fan of racing simulator games? You'll be surprised that this one is completely free and that it also has free online play as well and a custom track editor.
I don't know if I can post a link or not, so search for it on Trackmania's site.
I don't know if I can post a link or not, so search for it on Trackmania's site.