OK, my game systems are in two different rooms, my room, and my family room. Several systems are hooked up, some aren't. Here's what I have in each room...
My Room
NES (front-loader)
7800
SMS
800XL (shares RF cable with the 7800)
Genesis (shares hookups with the SMS)
2600 Jr. (not hooked up)
2600 Heavy 6er (not hooked up)
VIC-20 (not hooked up)
C64 (not hooked up)
Family Room
NES (top-loader)
SNES
N64
Gamecube
5200
PS2
PSX (not hooked up)
I have limited space for my room, BTW.