Hi Claz,
There are a number of BBSs online today, but I wasn't able to find any hosted on Amiga hardware. Here are a few resources for you:
http://www.telnetbbsguide.com/
http://en.wikipedia.org/wiki/List_of..._board_systems
I am "attempting" to set up a CNET based bbs on my A4000. I have a long way to go, and my X-Surf is "in the mail". With any luck i should have something online in a month or so. Not sure how practical or useful a BBS is for the modern age, but there are plenty of folks stuck with slow satellite connections that might find a Fidonet type of email platform of use. I'm really just setting this up out of pure nostalgia. My brother and I hosted the Camelot BBS back in the day and it was great fun interacting with other nerds prior to the Internet revolution.