I usually sell the games I don't play and invest in new ones, so my short list updates frequent. As of right now, it goes something like:
(these I play regular):
* Fatal Frame (like Silent Hill, except your entire arsenal is a camera.)
* Batman: Begins (actually quite good)
* Mercenaries (the only permanent game on this list)
* Star Ocean: Till the End of Time (takes 'til the end of time' to beat it.)
(some games I want to play more, but don't have time or interest right now):
* Lego Star Wars (don't judge before you try this masterpiece.)
* Predator: Concrete Jungle
* SSX3
(some random crap collecting dust):
* SSX Tricky (too old to sell)
* Tony Hawk's Pro Skater 3 (likewise)
* Tony Hawk's Pro Skater 4 (this too)
* Need for Speed: Underground (disc too scratched by, *ahem*, carkeys to sell it.)
* King of Fighters: Maximum Impact (No survival? No interest.)
* True Crime: Streets of LA (such a big potential, such a big waste.)
Royce, you might notice Midnight Club 3 isn't on the list. That's basically since I beat it - twice. 8)