Particles BBS is my main hangout. I originally hit it with my beloved
breadbin C64 using Jim Drew's Wifi modem. But I've since
migrated to my Amiga 1000 using Paul Rickards' awesome
WiFi232 modem. Jim Drew is about to launch his own
WiModem232 very soon, too, which looks simply awesome.
Particles is run on a C128D, and looks great in PETSCII but also works flawlessly in 80 column mode. Not to mention, I think the user experience that Particles offers is the most intuitive and clean out of any BBS I've hit.
I also hit Centronian about twice a week. It's much smaller, based out of Victoria BC, and run off a souped up C64. You really want to be in 40 column mode for
Centronian so it's full-screen. Gorgeous.
I also very much enjoy pinging Surf Shop 1-2 times a month.
Just in the C64 world, there are
so many. I'd be curious which are actually hosted on Amiga (and are active) these days.