So, anyone know fun stuff to do in it?

I really like the driving aspect of the game, and the storyline too, but it sucks because I have to run it on medium to low graphics to get a good (40-50) FPS that's playable. Anyone know of fun stuff to do, or worthwhile mods to install? Also, is it worth it to buy the other less-main-line games like the Ballad of Gay Tony and whatever that other one is?