For people looking for advice, and for those particularly interested in city maps, I've got a "Guide to RPG Map Making" on my website (far too long to post here) that you might find interesting. Lots of sample maps of different types and styles, as well.
I'd be more then happy to answer any questions about that page here (or in a separate thread, if the admin would like to keep this thread just for links).
Denis, aka "Maldin"
Maldin's Greyhawk http://melkot.com
Loads of edition-independent Greyhawk goodness... maps, magic, mysteries, mechanics, and more!