Check this site out, this guy made some remixes to some of the more popular tunes in FFXI's BGM.
It's pretty cool and sounds neat when you zone into the area after you have replaced your original bgws with them >.>;
The best ones in my opinion are Rolanberry Fields, Sanctuary of Zi'Tah, Heaven's Tower, and Tavnazian Safehold.
http://www.djplaeskool.com/musicdir.htm
He's got some other cool stuff, but I guess it depends on what music genre you're into.
Personally I like eurotrance, rave, and dance music.
These sound a bit more like house or hip hop, but nonetheless they sound pretty cool and it really spices up the BGM.