Free & open source Engine Management System including hardware and software. Downloads are available from http://download.freeems.org & documentation from http://docs.freeems.org additionally the forum is http://forum.diyefi.org/viewforum.php?f=19
This is yet another typical project lead by a narcisstic developer. Given the time it's been in development, not much progress so far, and it's likely to stay as low-paced in the future also. Few contributors stay for long. Likely to stay this way, and replaced by something better based on more modern hardware and saner firmware development models.