The site itself runs in a virtual machine running Debian 7.
Beyond that, various things come and go as needed.
I've been using Linux since about 2001, when someone handed me a Corel Linux disk. I've run through most of the major, and many minor Linux distributions, as well as all of the BSD's. For a while I ran FreeBSD, as well as Mac OS X, from 10.1 to 10.6. Debian has been a perennial favorite, from running cutietta.com's mail server on an old sparcstation 10(until spam overran the pitiful 2gb disk) to my current desktop and laptop, which run Opensuse. I even had a hand in a (failed) distribution, SimplyGNUStep, which never really got off the ground(various things just weren't there yet tech wise).
Rather than ask what I have run, ask what I haven't. At one
point, I've had Sparcstations, SGI Indy's, NeXTStations(I still
have that one), an Intergraph TD-10, various Intel/AMD boxes,
Macs, from the LC-II up the the Macbook, and various other