UPDATE:  I found the Fire Rock at a World Market on Saturday and bought it on your recommendation (I also picked up the Pipeline Porter, the only other they had there).  I really enjoyed it on Easter Sunday.  I'd gotten bored with IPAs but I think you've put me on the hunt again for finding some that are well done.  Thanks.
I'm familiar with St. Paul's Flat Earth.  I had their Cygnus X-1 Porter (I thought it was named for the gravitational anomaly in the system but the brewery's owner (I forget his name) said it was named for the Rush song(s) about the anomaly) when visiting St. Agnes (Frogtown?) for a fund raiser back in 2010 or 2011, I think.  It's not easy to get outside of MN, however I did find their Winter Warlock in the Berkshires when I visited there two Octobers ago.