The BASIC Stamp Discovery Kit (USB) is a great way to learn the Basic Stamp.
The Parallax StampWorks Experimenter Kit is a comprehensive collection of everything you will need to learn about efficient embedded design. This is a great package for those who want ALL the accessories!
The Robotics with the BoE-Bot Parts Kit turns your Board of Education into a BoE-BOT Robot.
This board is a great starting platform for learning how to take advantage of the Propeller.