That's a MessagePad 100, or possibly an OMP ("original message pad"). They are basically identical, with the MP100 having a newer OS installed (and was cheaper at retail).
These are, for the most part, good only as collector's items and basic PDA work. You can't do internet-related stuff until you move up to at least the MP120 (but if you're buying a MessagePad intending it to be useful, spent a little extra and get an MP2000 or 2100, which gives you 2 PCMCIA slots and full internet capability).
For what it's worth, I snagged an MP110 for approx. $100 Cdn last August.
They are cute as heck (in fact, I prefer the style of the 100 series / OMP, with the outboard stylus holder)... and if you get a couple, you can entertain yourself by 'beaming' things back and forth...