Seriously, how did this happen? I had like... five. Now I have (in the course of maybe two months when I realized I could run UMDs without issue with the custom firmwares) 16 or so.
Archer Maclean's Mercury
Exit
Darkstalkers Chronicle
Gurumin
Infected
Lumines
Metal Gear Acid
Metal Gear Digital Graphic Novel
Metal Slug Anthology
Puzzle Quest
Rengoku
Twisted Metal Head-On
Ultimate Ghosts n' Goblins
Untold Legends
Valkyrie Profile: Lenneth
Wipeout Pure
And those aren't even all the ones I want. Some of them I just picked up used as curiosities and junk, and there are a number of other games I'm interested in or just haven't managed to pick up yet. Pretty soon this will be surpassing my GBA library. Off the top of my head, I still want... Daxter, Bounty Hounds, Guilty Gear Judgment, Loco Roco (which I've played to death but still haven't purchased), Ratchet and Clank: Size Matters, and Metal Gear Portable Ops.
Someone save my wallet.