I found three sites out of the many that were alive before Geocities went kaput. Be warned though that Biab has over 270 RealTrack sets with demos so while most of the third party repository songs are midi, A lot refer to add on specialties that the improved versions of Biab don't have. for example harmonies I think have been recoded. I spent a lot of time organizing these and quite a few of them cause errors in the current version. But with so many Realtracks its not worth complaining. The deal is that because it is so easy to create a song and drag and drop into your sequencer with all of the processing toys. Its as fast to make something as it is to try to get all this old stuff to work. The PG site has many different worlds to explore. The video's are helpful under news and specials. Best of luck.

http://www.mmissary.com/p21.htm
and
http://www.midkar.com/MidiStudio/BIAB/List.html
and
http://www.alfwarnock.info/alfs/

but I have to say with all of the RealTracks that I feel spoiled that way and guilty for looking through the archives of older Biab.