With Himmeltwitch chugging along I started thinking about what tools and books would be good for building a city to use the buildings in.
First Cityworks by Fantasy Flight Games - a D20 supplement, and pretty nifty, it changed the way I layout cities, not so much the city design itself, but how I structure it.
A Magical Medieval Society: Western Europe - a D20 supplement with no D20 mechanics... a wonderful book, and the part that pertains to my current topic is available separately and for However be warned that it is a viscious, evil trap - while the portion given can be used all by its lonesome it will suck you into buying the whole book... Drat Expeditious Retreat for making a useful demo!
For software I use Fractal Mapper with the handy dandy city building from the Fool over to . Those tools chopped the time it takes me to map out a city to about a quarter or less of how long it took me without them. (And caused me to use Fractal Mapper a whole lot more often...)
For close-ups of neighborhoods I use . Though it looks like the project has stalled. (It happens with most mapping programs sooner or later it seems.)
What other tools and books are out there that I may have missed?
The Auld Grump
Glad to see you've got your Auld grfx, Aleph. You'll have to tell me how to do it! 
I tend to buy supplements for doing something myself rather than premade cities. (And I got Campaign Planner 2 and 3 for free. Thanks Phil, and Happy Bithday!) So while Sharn and Waterdeep look interesting I will be giving them a pass, since I do not use their settings. Now the old Cities of Mystery from TSR would be on the list, but it was well and truly tied to 2nd ed. AD&D.