Clustered? Hmmm. No. Not really sure how that would benefit me, or how I would go about doing it...
I do use the G4/400, PBG4/500 and the P3/800 as rendering slaves in Bryce. I haven't gotten Newtek's rendering nodes working yet under OS X so I've yet to use them with Lightwave. I have a love/hate relationship with them...
The Dual800 gets most of the attention lately. The G4/400 was kept around for use as a web server, but since I can't get DSL here, and my Cable modem is DHCP, I'm afraid that's out the window until I move to a new location. The PC is my test box for web pages and all stuff that people intentionally lock the Mac out of (b@st@rds).
The TiBook is the roving computer that usually resides in the living room, always on, useful for checking facts/email/macosx.com/macosxcentric.com instantly without having to enter the batcave and neglect my girlfriend.