I finally brought the Jalapeños home (had them at work for the first few months) and set them up with my GPUs on a headless, diskless (only storage is a 16GB USB flashstick) mining rig.
The motherboard, processor, and memory are castoffs I had on hand: a 3-GHz Pentium 4 on an Intel D945GNT with 3 GB of DDR2 (IIRC). In addition to the Jalapeños for SHA-256 mining, it has a 6870 and a 7750 for scrypt mining. A Seasonic SSR-550RM sits behind the Jalapeños.
The next photo is from an intermediate step in setting up the rig, without all the mining hardware plugged in (just the 6870 and one Jalapeño, off-frame):
Since I don't have a network jack close by, it's using a USB WiFi dongle. I might replace that with a PCI WiFi card. The flashstick doesn't show up, but it's plugged in underneath the WiFi dongle.
Patriot Autobahn flashsticks barely stick out of the port when they're plugged in.
For software, it's running Gentoo Linux. Two instances each of cgminer and CryptoSwitcher mine the most profitable SHA-256 coin and scrypt coin.
I intend to make up a frame with some aluminum extrusions to hold the motherboard, GPUs, and power supply. The Jalapeños (and the Bitfury miner that should arrive later this month) I'm thinking can just sit on one or two shelves. I'm thinking that when this happens, the rig will get moved out from under the bar and onto its own little rack of some sort.