Check this... an ARM BASIC chip for $10. Connect 3V, ground, and you can talk to this chip thru a serial prog on your PC. Program it in BASIC and you can control up to 22 digital I/O pins. That means 22 LEDs, motors, switch inputs, sensors, etc., so this single chip could become the brain of your robot project. It executes 10 million lines of BASIC/sec, which ain't too shab, and has hardware floating point (decimal precision calcs). This is like having an Apple II on a single chip except 50x faster. These gadgets probably don't appeal to most on this forum, but I really dig them. In fact, I'm feeling a quiver in my loins right now.
http://www.coridiumcorp.com/prod-specs1.htmlNote, I modified the original title so it's a little more applicable.