Google just launched My Maps, which provides a nice interface for creating your own custom maps with shapes, placemarks, etc. Idris posted the idea of using this as a tool for creating field maps.
Cool idea, I'm going to do this for our various pickup locations. I just played with this for five minutes, and it's really nice. You can draw fields. You can stick in placemarks, which users can click on to get the "directions to here" command. One thing: when you share the link, make sure you use the "Link to this Page" link. If you use your "My Maps" link then stuff like the Zoom and View (map, satellite, or hybrid) are not shared with the user, and the tool just zooms in as close as possible while still displaying all your custom objects (which is no good around here, since we live in the sticks and Google doesn't have imagery at that resolution).
Anyway, here's the result of my five minutes of fiddling.
