I had an idea that might be a simple yet invaluable addition to the current drawing tools:
Virtual Graph Paper: <a href="http://www.garrettbartley.com/graphpaper.html" rel="nofollow">http://www.garrettbartley.com/graphpaper.html</a>
With simple straight and diagonal lines snapping to a grid, you can do some amazingly creative things. I'm sure a few of us out there have hand drawn on graph paper for maps and such before, why not use it here?
I'd also suggest adding a separate layer for drawings, so we can separate our marks and notations from the maps and objects.