I've been looking for a great BB for some time, and I found it.. minibb! Wow! Like everyone said, small and customizable. Members of REAL discussion groups want to exchange ideas and info, and not try to dig out responses hidden amidst loads of silly graphics and strange signatures.
I do wish it had capability for a file attachment, and ideally, represent it in the message as a symbol to click on to either view or download the attachment. However, I think of it this way: it's an opportunity for me to brush up on my PHP and learn how to modify code. If I get such a hack working, I'll share it with all!