Make has put together a list of Open Source Hardware projects.
These are projects in which the creators have decided to completely publish all the source, schematics, firmware, software, bill of materials, parts list, drawings and “board” files to recreate the hardware – they also allow any use, including commercial. Similar to open source software like Linux, but this hardware centric.
Wikipedia: Open Source Hardware
[via Make: Online : Open source hardware 2009 – The definitive guide to open source hardware projects in 2009]