Well, somebody has to be first, so this is it. A site called HaloBunker.net has a modified version of Blood Gulch, with some weapon and vehicle modifications (namely, the LAAG fires rockets) as well as some movies of the modded map in action. Thanks Louis Wu at HBO.

Incidentally, that site is also running a contest, which ends October 10, on who can produce the "sickest" Halo PC desktop image. I think some of us here at Rampancy are too old to know what's meant by that.