Found this site (among many others) that gives different roof styles:
It is handy for adding variety to town maps.
Also, there is another style I have seen on some of the farmhouses around here, kind of a modified hip roof:
Nice find there. This makes for a good palette when doing top down maps, and you hit the "wow I've drawn the same roof fifty times" moment.
If someone has the time they could do all these in sketchup, providing the iso and top down appearance as a guild reference....