Nearly all computers in the room connect to one of two stations through various KVMs. More information on the NTI KVMs here.
Primary station:

Currently attached to the primary station:
Secondary station: Currently attached to the secondary station:
Networking comes in as gigabit to an Airport Extreme (single-band 802.11n), which then feeds the few gigabit capable machines, and a 24 port DLink 10/100 switch that feeds the rest of the machines. There is also an ancient netgear 802.11b wifi point allowing 802.11b use without degrading the 802.11g network.

There is a 27" curved screen CRT for gaming. The CRT is retained to allow the use of older light guns for duck hunt and the like.

Inventory of most systems:

Macintosh IIx:
Obtained from Ian Meyer in 2010 with 8MB RAM, a stock apple video card and an ethernet card. Replaced all aluminum electrolytic capcitors with tantalum variants. Replaced the solder-lead batteries with removable battery cases. Current configuration:

DEC VAXstation 3100:
An ebay purchase, the vaxstation arrived plain, no keyboard or video cables. Initially it ran with a serial console, but since then I've been able to piece together an LK201 keyboard, a BC23J-03 video cable, and a BC09J SCSI cable for it. I'm still looking for a mouse. Documented Ultrix install here

NeXT NeXTstation TurboColor:
Obtained off a 68kmla forum postwith a bare slab and a non-adb keyboard. Needing a sound box and an unobtanium Y cable to connect it, I purchased an adb soundbox from Black Hole, Inc., but the Y cable was prohibitively expensive. I went with ADB due to ease of integration with my existing KVM setup. The Y cable requires 13W3 connectors, which seemed to go for about $40 purchased individually, but premade 13W3 straigh cables were ~free. So I purchased a straight 13W3 cable and hacked it up sufficiently to have a working Y cable.

Obtained in 2003 in non-working condition off craigslist, I've since replaced the ram and all ROM chips with socketed versions in the course of diagnosing and repairing various issues.

Commodore SX-64:
An ebay purchase in 1999, I've lugged this thing around quite a bit.

Performa 6400:
Obtained as part of a large lot acquired in 2009, which included the SE that formed the case of what now houses the SE/30, Mac Classic, a number of keybards, printers, etc.

PowerMac G4 AGP:
Sawtooth in a Blue & White G3 case.

Obtained from a forum post on nekochan, the machine did not survive shipping very well. Originally, it had 256MB RAM, but half the RAM did not survive shipping. The case didn't survive particularly well either, there are a lot of broken and missing pieces.

SPARCStation 20:
Obtained for free off a craigslist posting in Spokane, WA, I picked it up on a visit there. It also came with an Ultra1 and 2 21inch Sun monitors. I've since upgraded the rame, replaced the disk with SCSI-IDE-CF, and upgraded the CPU.

HP 9000 712/60:

Quadra 700:

SUN classic:

G4 mini:

PowerMac G5:
Obtained from Brian Mastenbrook the machine is one of the few machines that arrived totally serviceable.

Macintosh SE FDHD:

Apple //c:
Received mostly dead, repair documented here. Has the accompanying monochrome green phosphor display. It has survived a couple attempts at retr0bright.

Macintosh SE/30:
The case was obtained as part of a large lot of older Mac gear, I did heavy modification of the interior of the case to replace the SE logic board with an SE/30. The RAM is maxed out, and has both ethernet and external video cards in it with the help of a right angle 030 PDS connector inserted into the ethernet card's passthrough slot intended for IIsi operation. The logic board has had all aluminum electrolytic capacitors replaced with tantalum variants.

Macintosh Classic:

Cobalt Qube2:

Macintosh ColorClassic:

Performa 6214:

Quadra 630:

PowerMacintosh G3 Beige Desktop:
Obtained for free in 2001 through a friend with a logic board replacement in 2002.

4U PC:
Assembled new in 2001, running largely unmodified since then. This is currently used as the EPROM burning station and JP1 TV remote programming machine. Both require real mode software directly accessing the parallel port to control external devices.

Apple IIgs:
Obtained from Ian Meyer in 2010 in completely stock configuration, I've since discovered a lot of new hardware development for the AppleII platform I've embraced for this system. Initially I tried netbooting, documented here. I used the Quadra 630 as the server. The Uthernet use is documented here, and the iDisk use is written up here.

Quadra 900: