....and I don't know what game to spend it on. I only have a PS2 (no Cube), and currently the only games that have come to mind are :
XIII Beyond Good & Evil.
The only thing is that those are multiplatform and big name games, and I'm sort of looking to add some under-rated, unique niche games to my library (to go along with games like Rez, Silpheed, and Disaster Report.)
I wouldn't call it underrated, being as it's an awesome game, but Twisted Metal: Black is in the Greatest Hits collection and is the best car combat game I've played. My wife is enjoying Sphinx and the Cursed Mummy now.