I was a member of the Hive until it went down, now the main other chemistry forum I frequent is Wetdreams, an offshoot of the hive, is where most of the bees in diaspora now rest their wings and set about the communal honey discussion.
I was a member of sciencemadness, but I can't remember my username or password since the unpleasant incident a couple of years ago with the fed, I haven't reregistered yet, but I lurk and read.