A followup to the line-follower robot post, the LineBot project by bithead942:
LineBot leverages an Arduino Uno which helps to decrease the complexity. I also used an Ardumoto shield for motor control (I’ll pre-solder the headers and screw terms). Using these will help accelerate the build since it means fewer parts on the breadboard and easy programming. LineBot also uses the Magician’s Chassis from Sparkfun. This is a great kit and is very inexpensive.