OK. I'm cheating a bit because my setup now has an Intel Mac, but I still have PPC machines doing their thing.
The Apple Cinema HD Display and HP monitor on the left belong to the newest addition to my stable: a Mac Pro 1,1 2.66 Quad, named Suzan, running Snow Leopard 10.6.8 with 4 GB of RAM and 2.25 TB of drive space among 4 drives (3x500/1x 750GB). The Cinema HD display and HP monitor are driven by an Nvidia GeForce 8800GT with 512 MB of VRAM.
The HP monitor to the right is connected to my G5 Dual 2.0, named Gretzky. After my first G5 died on me in an unknown manner in early August, I decided to cobble parts together from it and the spare G5 I had that was doing DVD encoding. This G5 now has a 128MB Radeon 9600XT video card from the dead G5, 6 GB of RAM from both machines, and 570 GB of space between two drives (250 GB/320GB). I may add drives later for movie storage later, but that's in the future. Gretzky runs a strong Tiger setup.
The MDD in the middle is a G4 Dual 1.25, named Liz, that I have converted into a server. This G4 has six 500GB IDE drives that I picked up last year. I had originally used these drives across multiple G4 machines, but after two MDD Dual 1.0s flamed out on me and the DA 466 got to be too tiresome to maintain, I took out the DVD drive and cage and installed two hard drives in its place. It is connected via Radeon 7000 to the Studio Display. The Pro Speakers are also attached to this Mac and it functions as a jukebox and movie player when I have other Macs on the bench for repair.
The DA 466 on the far left is currently on hiatus. I re-installed the original CD-RW drive in order to read my MacOS 9 CDs from yesteryear. It has three drives inside: the boot 80 GB and two 120 GB drives for storage. One drive is stacked on top of the boot drive inside an MDD cage on the floor of the Mac, and the other drive is inside the slot reserved for the Zip drive. It works and I'm fine with that.
Eventually, I'll get around to reinstalling Tiger and the PC SATA card I had in there.