Compact size, not much power draw, should be very reliable (no Windows). Some have a decent amount of I/O, including serial (e.g. want to talk to GPS).

But, I/O is going to be 3.3V or 5V, so you'd have to wire to relays to handle more power.

There are various kits available new from $40/$50 (e.g. Luminary Micro). Of the two I mentioned, the Zilog is more capable, but more work; but it does have a pretty active Yahoo group.

I've had to narrow my focus, so I'd be happy if someone else can find a use for stuff that's now extra. The following links should be close to what I have (I'll have to check the boxes to be certain):
[link|http://www.rabbitsemiconductor.com/products/bl1800/|Jackrabbit]
[link|http://www.zilog.com/products/partdetails.asp?id=eZ80F910100KIT|eZ80]
--Tony