The "Official" HM site: http://www.heavymetal.com/
John Findley's Tex Arcana was one of my favorite HM stories. He has it all online, with some edits, and a fourth book in process. Not updated frequently (just a couple updates in the last couple years) but still really cool: http://www.texarcana.com/
Rod Kierkegaard Jr. did Rock Opera in the 80s, which not everyone liked but I did. He's still writing, his Obama Jones and the Logic Bomb is futuristic and very enjoyable, you should read it. And his other stuff too. His blog hasn't been updated in a few years: http://rodkierkegaard.blogspot.com/ but he's more active on twitter these days: twitter.com/rodkierkegaard
Ben Michael Byrne put up some Kranburn on the old HM forums, and there was a webcomic I linked, but it's gone now, I don't know what happened. He seems to bounce around a bit, but I keep looking to see if Kranburn ever reappears: BMB Fbook, NSEW Fbook,
I like Por Por Books Blog and I visit it often enough that I decided to put the link here. A range of SF and other reviews, with a healthy helping of HM, presented with a bit of perspective from the times they came out, and many scanned images of covers and pages. The author's viewpoint has enough similarities to mine, viewing things as they appeared at the time, with a bit of dry wit, for me to find it appealing. Hope you enjoy it as much as I do. http://theporporbooksblog.blogspot.com/
heavymetalmagazine.tumblr.com/ a now-comic-artist putting up a scan a day of HM pages, from his late father's collection, with a critical but appreciative eye.