Kimba...."privacy" is obviously a fluid situation these days.
People can find out all kinds of things about you that were much more
difficult in the past.
Facebook users can face a potential privacy issue, but random message boards like 3DHS,
that are not high profile and where you are not "seen" really should not be a problem
unless you are going to a job where a deep background check is being required.
Just sign up for message boards using a more anonymous type e-mail (hot-mail/yahoo mail)
Then pick a user name that is anonymous as well.
That should keep you "off the radar".
I have been noticing more and more "comment" sections
on publications like newspapers, magazines, web-sites
are making it real easy to sign in and make comments
with your Facebook log-in. For privacy reasons I do not
ever sign in and make comments under my Facebook name.