If you're on gopher, there's a very good chance you already know 
about SDF. That being said, I was actually introduced to SDF
through gopher... I was poking around at internet technology on
my 8088 when I stumbled on gopher (I didn't use it back in the
day, I went straight from BBSes to HTTP.) I found floodgap, and
then SDF was suggested to me by a gopher user. 

If you haven't had a look, go to SDF.org to get started. If you
appreciate a *nix shell (I have since Slackware 3.x) then you'll
be right at home. There are some interesting sdf-specific things
too, such as bboard (command line bbs of sorts), com (command
line chat of sorts) and anonradio.net, an underground streaming
radio of sorts. All are worth checking out.

For anonradio.net, make sure to tune in to snowdusk's show. It
is worth the scheduling. It's a live show, so use "com" or irc
to chat with everyone else listening live!