Glad people are enjoying it, it was a nice diversion to get back to pen & paper for a bit - and then to discover the useful GIMP tutorials that let me take pen & paper into digital. I didn't have a particular plan, beyond thinking it was going to be a mix of natural cave and hewn/constructed spaces. No pencil sketch first, either, so not only was I making it up as I went, I was committed as soon as the pen started moving.

Here's the white background version, obviously cleaned up from the photo but with the parchment effect layers turned off.
Click image for larger version.  Name: dungeon30Oct2012_white.png  Views: 963  Size: 2.71 MB  ID: 49551

Same size as the parchment version, so it should print fine if that's what you're planing. Also obviously easier to edit.

I've just learned that I'm off for a two-week field assignment with my company, starting this Sunday! I don't own a laptop or netbook, so I'll take my notebook (as in actual paper book...) and should have lots of downtime in my hotel room to sketch and draw maps...