Oh man, this thread is making me nostalgic for my days playing around with PPC Macs... Nothing like the OP's collection, and living in flats I never had the room to store many of them for very long, but I think I've at one point or another owned most PPCs: G3/G4/G5 iMacs, 12" G4 Powerbook, iBook G3 Clamshell and G4, eMac G4, most PowerMacs G3/G4/G5 (never a Cube though!)... Sort of wish I could still justify it.
I am a big fan of keeping old Macs going for as long as possible though, and by the standards of the Intel forums my current household machines are pretty old: 2010 iMac, 2010 white unibody MB, 2013 Macbook Air, all kept going through occasional 'surgery'.