The Basic Stamp is made by Parallax, Inc. They sell a small range of Basic Stamps and kits that are aimed at the novice hobbiest. Each Basic Stamp module is a full computer on a DIP-chip. It runs Parallax's PBASIC language, has built-in memory, and programmable I/O. The company also offers many accessories that are made to work with the Stamp. Here are some links to useful material on their website:
One of the advantages of using the Basic Stamp is that they have gained a large user-base over the years, and most of the code will work on any Stamp - just copy and paste.