I didn't think I had many, but when I look around...
A few PCs & Macs (some belong to my wife)
Commodore 64 (several)
Commodore 128
Amiga 500
Amiga 1200 (w/ 1gig HD, CD-rom, etc)
Atari 2600 (a few different models)
Vectrex (broken)
NES
Sega Master System
three Gameboys (one gold Pocket I just sold, waiting for payment, one Color up on eBay now, and one old model I just found in the dump)
SNES (with Super Wildcard backup unit)
N64 (a friend has my Doctor V64 backup unit)
Saturn (in negotiations to buy a chipped one, then will sell my old one)
PS1 (chipped, about to be sold)
Dreamcast (with a couple hundred games I don't get time to play!)
PS2 (chipped - just picked this up at a garage sale a week ago, so cheap I had to pinch myself)
Gamecube
That's probably it. I think I just gave my last Genesis away to my Dad's friend's kids.
I would feel terrible for having all this stuff, but 99% of it I bought for next to nothing at garage sales, or found in the local recycling centre (you wouldn't believe the stuff that gets dropped off there!). The exception is the SNES & backup unit, both of which I bought new when I was a kid and they first came out.
My favorite out of the whole lot is probably... a three-way tie between the C64, SNES and Dreamcast. Although the A1200, NES and Gamecube are pretty damn sweet too.
But I predict my new favorite will be... the GP32! All I have to do is decide between Lik Sang and a 180mhz GBAx unit... I'm the worst person in the world at making decisions!