OK, here's what I was able to see, I had to take a notepad with me.
Nintendo: NES, Super NES, N64, Gamecube, Wii, Gameboy, Gameboy Color, Gameboy Advance, DS, Virtual Boy
Sony: 4 different PS1s including a blue "debugging" PS1, 4 different PS2s (two are the old fat style, one is a thin and the other is a fat one that is a debugging PS2 and says "TEST" where it usually says "PS2") PS3 (this is the only one of all these consoles that is actually mine)
Sega: Master System, Genesis, Sega CD, 32X, Saturn, Dreamcast, Game Gear
Panasonic: REAL 3DO
Atari: VCS (2600), Lynx
NEC: Turbo Graphx 16
SNK: Neo Geo Pocket Color
Coleco: Colecovision
There could be more but that was all that I could see. Most of those systems (except the PS3 and Wii) are in one room, which is a cluttered mess full of games.