Introduction: Single Sided Really Bare Bones Board Arduino in EAGLE.
Paul Badger of Modern Device Company designed the "Really Bare Bones Board" (http://moderndevice.com/RBBB_revB.shtml) and placed the design in the public domain. (Thanks Paul!)
I've converted the design to the EAGLE CAD package, and in the process I noticed that you can pretty much make it into a single-sides board as well, probably not to hard to make using hobbyist materials.
Design files here: https://docs.google.com/leaf?id=0B6dMB5dovDUZNTEzODE4NmEtMDZjNy00YWQwLTg5OGEtNzNiYmJhZmJjODI4&hl=en