a lot! you can go to VC Vault computer in the 3rd level and evrytime u use it u gain 20,000 exp, u can also go to New Reno and visit father tully and he will give u the hint book that will make all your stats into 300 or go and find all the special random encounters or kill everyone.
"I am the night,I am the day,I am the light gone astray, the fear that's in your bone that is I, I am the taker of souls"
The problem with those things, is that they're pretty much pointless after you beat the game, I'd just start over and experiment with a new type of character
"I am the bringer of death, and the cry of sorrow, I am the one who... ah hell, I broke a nail."