CPU support: Pentium P55C, Cyrix MII, AMD K6-2
FSB support: 50MHz, 60MHz, 66MHz, 68.5MHz, 75MHz, 83MHz
PSU connector: Proprietary (not AT-style - 5VSB and PS-ON are present in the P8/P9 connectors)
I/O: 1x serial, 2x USB, no RJ45, audio (line-out, speaker out, microphone in, front headphone out)
I don't know if you want the expansion slots on the riser listed here, but the riser has 2x PCI slots. There are other risers with 1x ISA slot or 10Base-T Ethernet as well as the PCI slots. I'm a little curious about the power delivery problems that were mentioned.
I also have a new board to add. It's a Gateway Anigma 586. I don't know how to handle the optional features on this board. My camera isn't very good, but I have pictures of one without audio or video (and with the power supply fan header desoldered).
Form factor: ATX
CPU: Pentium P54C and P55C
Power connector: ATX
Chipset: Intel 430TX
FSB: 60MHz or 66MHz
RAM: SDRAM, maximum 256MB
Video (optional): ATI RageII+, 2MB of RAM
Audio (optional): Ensoniq ES1370
I/O: 1x floppy, 2x IDE, PS/2 keyboard and mouse, 2x USB, 1x parallel, 2x serial (1x DE9, 1x header), infrared, 1x VGA (optional), audio (line out, line in, microphone in - optional), 1x gameport (if audio is installed)
Expansion slots: 3x ISA, 4x PCI (3x PCI if audio and video are installed)
This board has a really strange and crude switching VRM circuit, but I don't know if it warrants an "insufficient power delivery" warning. One USB port can be routed to the front or back panel.