For PS1 and PS2, I probably have 100+ games in my possession right now, and have probably owned 200+ since I got my PS1. I usually don't play my PS2 anymore, but I keep it just in case. I want to mod for.. backup.. purposes.
I still own a N64 and maybe 3 games for it (off the top of my head, Goldeneye, Star Fox 64, South Park Racing)
Now, my prized collection is with my PC games. Every game I own for PC I have played at least 4 or 5 times, and if I don't play it anymore it's because I don't have the time to. I probably own well over 100 games for the PC and don't feel like listing them all on here. Just to list some to give you a general idea of what I like: Microsoft Flight Simulator 2002, 2002 Professional, 2004, and FSX (don't have Acceleration, sadly), Command and Conquer: The First Decade, Command and Conquer: Tiberium Wars and Kane's Wrath, Halo 2 for Vista, Sim City 2000, 3000, 3000 Unlimited, 4 with Rush Hour expansion, and Societies, Rollercoaster Tycoon 1 with all expansions, 2 with Wacky Worlds expansion and 3 with all expansions, and in my opinion no true collection is complete without World of Warcraft and the Burning Crusade expansion.
I could list them all, but I don't wanna. I am really into RTS and simulation games. When I get my new GPU and 2 more gigs of RAM next week, my game collection will sure live up to it's name as I am going to play the hell out of all of them.