Adrian Wong of Adrian's Rojak Pot has been building up his BIOS guide since late 1999. Today, he hit version 6.0, and the guide is now comprehensive in its scope. It comes highly recommended from me due to the fact that BIOS optimizations can yield positive results in performance and compatibility for everyone. Adrian also goes into far greater detail than even your best motherboard manual and even debunks some "myths" that some manufacturers still propagate.
That, and you may find a familiar name among the information. :-)