I've found a few motherboards which offer parallel ports. They're small, with cheap hardware.
Like these, which have almost the exact same hardware:
http://www.newegg.com/Product/Produc...82E16813157498
BIOSTAR J1800NP Intel Celeron J1800 2.41GHz Mini ITX Motherboard/CPU/VGA Combo - Newegg.com
Open Box: ASUS J1800I-A Intel Celeron Dual-Core J1800 Mini ITX Motherboard/CPU/VGA Combo - Newegg.com
Or these, which are a bit different:
ASRock AD2550B-ITX Intel Dual-Core Atom D2550 1.86 GHz Intel NM10 Mini ITX Motherboard/CPU/VGA Combo - Newegg.com
GIGABYTE GA-E2100N AMD E1-2100 APU 1.0GHz Mini ITX Motherboard/CPU/VGA Combo - Newegg.com
http://www.newegg.com/Product/Produc...82E16813157565
They're all fanless, which keeps the crap out. I've got an appropriate enclosure. I actually think it's the same enclosure Tormach uses. Could use a solid state drive.
These should have enough power, but I'm curious what else I should be looking for in a dedicated LinuxCNC system.