My friend has made a wiki about running marathons (and half marathons, no ultras) around the world and is looking for contributors! I thought this would be a perfect place to post.
Here is the link to the wiki:
At the bottom of the page, you should find a link for signing in. There you can make your free account. Add comments to races listed on individual pages and/or add marathons and/or half-marathon races you have run that aren't listed.