The GoodFET is an open-source JTAG adapter, loosely based upon the TI MSP430 FET UIF and EZ430U boards, as described in their documentation. See Improving the MSP430 FET on Travis Goodspeed's blog for further information.
In addition to JTAG, the GoodFET has been inspired by HackADay's Bus Pirate to become a universal serial bus interface.
Hardware and software are available under the BSD license, and free-as-in-beer boards will be given to those who ask politely. Email Travis Goodspeed, travis at radiantmachines.com, to get involved.
For source code, schematics, and firmware
svn co https://svn.code.sf.net/p/goodfet/code goodfet
For development, use your sf.net account.
svn co svn+ssh://email@example.com/p/goodfet/code goodfet