My name is Jeremy Bulloch, and one of my long-time gaming buddies turned me on to this forum. After a several year lay-off from running a regular RPG, and only playing sporadically at best, I'm taking the plunge back behind the screen to run an after-hours game for a group of my customers. I'm looking to beef-up my map-making skills, especially for urban designs. Mostly I just use Photoshop, but I'm always willing to listen to advice from more experienced cartographers.
Welcome to the Guild, Jeremy. While you can use PS to do urban designs using a vector program like Illustrator or Inkscape in conjunction (even if only for labelling) is something you should look at. We have a few tutorials on city design (see my signature for one of them) but these are more fantasy based rather than modern (if that's what you were after).