So many great games mentioned already. I'd like to add:

Megaman Legends
Tomba
Coolboarders 3
Jet Moto
NFL Blitz (not a playstation exclusive, but still)

and mothersmurfing Blasto, son. Say what you will about the gameplay (personally I loved it), but the game is worth it alone for Phil Hartman's wisecracking the whole way through. Sad that you're not still with us Phil, but you live on through Blasto and Lionel Hutz.