There are PCMCIA USB cards out there, some for as little as $30 I've seen.
The question is, will they work with the SimPad?
That'd be swell if they would
Then again, I suppose there aren't any USB drivers for OpenSimpad, though...
Sounds like it could be quite the project...
I think I'd be up for at least messing around with it if I end up buying a Simpad...