I thought I had responded to this ages ago, but let's see... off the top of my head but I did just recently pack up most of my stuff in preparation for putting my house on the market so I should be pretty fresh:
Nintendo
NES -- Front-loading x3, Top-loading x3 (1 composite modded, 1 component modded)
SNES -- Regular x2, Mini x1
N64 -- x2, 1 RGB-moddable (haven't gotten around to it yet)
GameCube -- black, with Gameboy Player and Broadband Adapter
Wii -- White
WiiU -- Black Pro System
Gameboy -- original
Gameboy Color -- x2 I think? Blue and Purple?
Gameboy Advance SP -- x4 total -- NES themed, AGS-101 Pink, Black, and Silver
Custom Consolized GBA
Virtual Boy
DS Lite -- black
Sega
Master System
Genesis -- Model 1, Model 2 (x2 I think)
32x -- x3 (? Maybe only x2) -- One S-Video modded
Sega CD -- Model 2
Saturn
Dreamcast -- x2 (at least)
Game Gear -- x2 (at least)
Nomad
Sony
Playstation -- at least 1, maybe more, forget which version
Playstation 2 -- x1 fat with Broadband Adapter, x1 slim, possibly more
Playstation 3 -- slim on CFW
PSP -- 2001, silver
Microsoft
Xbox
Xbox 360 -- slim
SNK
Neo Geo AES -- Component Modded
Neo Geo CD -- Component Modded
Neo Geo Pocket Color -- silver
Atari
2600 -- multiple 4-ports, 1 S-Video modded
5200 -- 4 port, S-Video and power modded
7800 -- S-Video modded
Jaguar
Jaguar CD
Lynx -- Model 2
Misc Consoles
Colecovision -- Component modded
CDi -- 400 model I think
Odyssey^2
3DO FZ1 -- sold!
3DO FZ10 -- sold!
Vectrex -- sold!
Arcade Hardware
Neo Geo MVS -- 4 slot in a dedicated Big Red cabinet
Capcom CPS2 -- Green A-Board, Blue A-Board (not working)
IGS PGM
Sega ST-V
Sega NAOMI -- with Net Dimm
Taito F3 -- Region free
Altered Beast -- with System 16 to Jamma adapter
Custom supergun built by Jamma Nation X
... I think that's it, hardware-wise. Good god I might have a problem.