A
tutorial on how to make isometric pixel art, à la the pixelicious
Eboy.com. It's pitched at beginners, though has some useful hints. From what I gathered, Eboy's system is somewhat more sophisticated, with modular libraries of elements (buildings, street scenes and so on) that they can plug together, and possibly some sort of Common Lisp-based compositing engine, but this should work.
(I was thinking that someone should do an Eboy-style streetscape of Brunswick Street. Perhaps, once I figure out the forking-into-infinite-numbers-of-parallel-universes trick, I'll do it.)