Personally owned?
Nes
GameBoy
SNes
PS1
N64
GameCube
GBA
And now a slim PS2.
Must say that with each passing gen, I spend less and less time with them.
As for jointly owned with kids in my neigborhood:
Just about all of them. We would swap sometimes for fun, but our folks didnt always like that.
Played All 3 classic Ataris.
Sega Master
Sega Genesis
Nintendo Virtual
Coleco
Commadore
CD-i
3DO
TurboGraphix
Sega 32x
Sega CD
Saturn
Dreamcast
NeoGeo
Jaguar
Lynx
Xbox
The only console I havent swapped with a friend is the 360, and thats because nobody wants to give it up for a week.
Did get to play with one at a GameStop (or was it GameCrazy?).
EDIT:
HOORAY FOR CLASSICS!
http://www.vgmuseum.com/ads/classic/