I finally got a group of strong men to carry the rack into the basement, and loaded it with computers. There's still a LOT of work to do on it, but this is a milestone of sorts.
Top to bottom: DECserver 900/TM, HP StorageWorks DS2100 ("pizza box"), HP Proliant DL380 G3, IBM eServer x346, IBM eServer x345, HP Integrity RX2600 Server (running OpenVMS v8.4), IBM eServer x336 (1U), empty space, home-grown AMD Athlon 64 X2 box (running Debian 6.0 - my primary workstation), and HP Proliant ML350 G4.
The four computers on the top are "junkers" that I put together from various components bought on the cheap through the local auction site.
The rack has a back door which hides most of the cabling.