Google Maps Mania spotted a very timely mashup: Brian Timoney's super-duper marthon map. The map has kilometer and mile markers, and shows the full path of the race. Most important, however, it shows where the port-o-potties are-- because nothing is worse than running 26 miles and not being able to stop to pee.
Other NYC map mashups that we're digging: NYC in the Movies, SliceNY pizza map, and the Williamsburger community guide.