MediaTomb

From Admin-SIG

Sourceforge reports that this uses mySQL (or a lightweight SQL database) for media libaray. This is a good feature. mySQL is recommended for better performance, but its a little more work to set up a mySQL server.

Like the other two UPnP servers mentioned, this does not YET have transcoding support. AFAIK, you need a commercial product to get transcoding at this time.