oh my, out of boredom, I searched Yahoo! for Excelsus! BBS and found someone mentioned it in forum in 2003!
http://www.clinteastwood.org/forums/index.php?topic=1199.0
Excelsus BBS ran on an Atari 520STfm and then an Atari 1040STf from 1988-1992. 1st only on single sided, 360K 3.5" floppy (BBS software AND data!) then ended up on a 50MB hard disk. It was actually one of the 1st (maybe THE 1st) BBS in Hampton Roads, Virginia to have blazing fast 2400baud access. Only had 1 phone line the entire time.
I wasn't a very active user on Excelsus! but I do recall it. In fact, I stood before that ST in your house once - I saw where the magic happened. :-) Prob sometime in '89.
I was a big BBS user, but stuck more to PenCoCo, The Blues Exchange, Volksboard TBBS, OxGate 007, and The Board.
I recently put together a 520ST system though, for nostalgia.
http://www.flickr.com/photos/blakespot/sets/72157604329654261/
I owned a 520ST back in 1986-88 or so. Good times.
blakespot
a few years ago threw an atari st into the trash, it was severly messed up. But it still sadden me.
Somewhere I have my 800xl stuff, I need to get that set up.
Btw, I tried the same search "excelsus bbs" (with quotes). Google found nothing so Yahoo! Windows (must be the "!" at the end ... Excelsus! BBS ... Yahoo!)