I've always thought about making a multi part tutorial on battle maps/encounter styled maps as well. just haven't been able to find the time. My stuff still isn't the best looking but I understand most concepts on how to execute. What makes a dungeon look good or have that extra oomph is hand drawn or custom objects. You can do reasonable work with pre-generated objects from the dundjinni forums and such locales, but when doing it yourself it ends up match the general mood and vibe of your dungeon. Unfortunately I only use GIMP so far so that may cause issues, but I'm willing to do live demonstrations on some techniques and stuff I've picked up.