To Ascension:
This is more or less exactly what I've done. Cut out individual segments of texture and transformed and rotated it to death to fit each angle and shape of rooftop. Takes forever, especially because you should really only rotate a segment once. If you keep rotating one piece of texture 5-10 times, it will become too blurred. So it was like "rotate 68,5 degrees->no, doesn't fit the angle quite right->undo->rotate 69 degrees". And like you said, the eventual result is crap.

To RobA:
No, this map is done in Photoshop, so the houses are done with the a standard bevel style applied to a masked layer. But I really like that script, it seems just like the think I'm looking for. I'll see if I can't get what I have to fit into GIMP.