If you want to have an online listing of what you've got you can go to here:
http://backloggery.com/ There are other sites as well.
I've got a decent collection of everything from NES to N64. I do have some PS2, DreamCast, and GameCube games too. If you're actually interested in playing games, particularly expensive ones, you should buy a Flash Cartridge. Certain good games like Little Samson for NES go for well over $200 as just the loose cartridge. The game definitely isn't worth that as a game. But it is a game worth playing. This theme repeats itself with lots of games. Games which are very good but cost obscene amounts of money now. The problem is that retro game collecting is in a fad like stage.