MarathonGuide.com is a site that I found last night that has the best list of marathons that I have yet seen. I am in the process of trying to find at least one but preferably two marathons that I can run this fall, and I searched a variety of sites to see what was available. I searched , I searched , and MarathonGuide.com. Anything that I found on the first two sites I also saw on the third site, as well as a few others.
It is fairly easy to find the races you are looking for, and it provides information about the race as well as Amazon style user comments/ratings about the race. You can see statistics about the number of finishers and winning times.
I managed to get a list of 7 races in the New England area (that were not in Maine or Massachusetts) this fall in a fairly short time. They also have product reviews and articles, which I have only begun delving into.