I started using irc in january of 2008, about the time I started using linux.

I'm on foonetic and subluminal (a new network, about 6 or 7 months old). foonetic is host to the various #xkcd-<whatever> channels, as well as the main #xkcd channel. subluminal is just something some friends of mine put together. the average user count is in the twenties.