My biggest obstacles are that it doesn't have an ethernet port and that it doesn't have BIOS USB support (although it does have a card with two USB ports).
I've managed to run some small Linux distros on it (I'll definitely try this one), but, you're right, I haven't really found anything useful to run on it.
I have P1 90mhz P2 500mhz and typing from P4 just now :P
I think biggest limit will be missing SSE2 PAE POPCNT modern distros need this