- MarathonGuide.com: If you're looking for a marathon to run, don't miss this site. It has the most comprehensive listings of U.S. and international marathons and is a great way to research a specific marathon. Many of the entries include pages of ratings and reviews from runners who have done the marathon.
- Coolrunning.com: This site makes it easy to find exactly what you're looking for by allowing you to search for races by location, race distance, date, and event type (triathlon, relay, kids' races, etc.).
- Racevine.com: This relatively new site was built by racers/computer geeks for the racing community to share their experiences with others. You can write reviews -- the good, bad, and ugly -- about races you've done, and search for new races by race name, location, date, or event type.
- Active.com: Most runners are familiar with active.com, which boasts the world's largest directory of sports and recreational activities. The site also offers online registration for many of the events listed on their site.