Thought this was pretty cool.
http://www.openecu.org/index.php?title=EcuFlash
EcuFlash is a general-purpose ECU reflashing and editing tool that supports an ever-growing list of vehicles. EcuFlash uses the OpenPort vehicle interface to reflash vehicles via the OBDII port. EcuFlash also allows you to edit ECU data (known as 'maps' or 'tables') in a human-readable format using a XML-based definition system to translate the data. With properly setup definitions, the ROM from any vehicle can be edited. Future plans for EcuFlash include logging support / overlay, live tuning, and 3D visualization.