If you create your own maps digitally, what do you use as map-making software?
Personally, I am fond of Inkscape, as it gives me maximum flexibility and the vector-based approach is great for scaling and rotating things.
Tiled. You can even cut up (in Gimp) a bunch of other maps and create your own tilesets. So now I have a bunch of them, one with most often used rooms, one with basic walls, one with security measures etc