I've been using the simple drawing tools in Apple's Keynote, along with some fantasy icons, fonts, and clip art to generate simple, schematic maps for a campaign I'm working on.
The buildings in this one started as a Victorian house from Open Clip Art (http://www.openclipart.org/detail/49117) that was modified in Photoshop to create 4 or 5 different sizes and styles. Pieces of the map can be easily shuffled around as individual elements in Keynote... much simpler than using a drawing program.
Thoughts?