Each year Phillip Torrone (MAKE senior editor, creative director here at Adafruit) writes a “definitive guide to open source hardware projects” for the year, 2009′s is up and it’s MASSIVE. These are all 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.

This year there are over 125 unique projects/kits in 19 categories, up from about 60 in 2008, more than doubling the projects out there! – it’s incredible! Many are familiar with Arduino (shipping over 100,000 units, estimated) but there are many other projects just as exciting and filled with amazing communities – we think he’s captured nearly all of them in this list. You’ll see many kits from Adafruit, EMSL, SparkFun and more. Grab some hot chocolate, get comfy and spend a few hours checking out all the great projects!