Heh, cool topic, a bit of retro-flexing. My list:
2x Dreamcast (seems like a trend in the forum)
Mega Drive + Sega CD
Gamecube + Game Boy Player
Except for the Saturn every console gives me access to more than one library, which I appreciate. I also have a Retro PC (Dual Pentium3 + Voodoo5, W98 / W2k), don't know if it counts.