Marathon of Britain
- News, the team, photographs, faq's, and community.
- http://www.ambitionevents.com/mob/

Sri Chinmoy Marathon Team New York
- Multi-day events, including an annual 3,100-mile race. Information on upcoming races and events, articles, and contact information.
- http://www.srichinmoyraces.org/us/

Endurance Sport Club
- International organization, based in Canada, that sponsors a number of fat-ass style ultra-races. Includes membership information and race calendar.
- http://www.clubfatass.com/

Multidays.com
- Resource for multi-day events with calendars, news, results, and training information.
- http://www.multidays.com

Team CRUD (Coloradans Running Ultra Distances)
- Ultra trail running information, photographs, news, and links.
- http://www.teamcrud.com/

Ultra Adventures
- Comprehensive regional ultrarunning resource focusing on North Carolina and the Mid-Atlantic region.
- http://www.ncultra.org

Kevin Sayers UltRunR Site
- Resources and opinions on topics ranging from training and racing tips to equipment recommendations.
- http://www.ultrunr.com/

Cascade Running Club
- Hosts 100 mile, 50 Mile and 50K minimalist runs in Washington. Includes club information and race details.
- http://www.cascaderunningclub.com/

The 100km Association
- Club serving Britain. Includes news and events, club information, message board, and race results and reports.
- http://www.carey.abelgratis.co.uk/100km/index1.htm

UltraOz
- Includes news, links, and race descriptions.
- http://www.ultraoz.50megs.com/

St. Louis Ultrarunners Group
- Provides club news and events, including registration materials.
- http://www.stlouisultrarunnersgroup.net/

Kansas Ultrarunners' Society
- Includes event descriptions, member biographies, pictures, newsletters and membership information.
- http://www.ultrarunners.info/

Sri Chinmoy Marathon Team International
- Sponsor of multi-day races, including the world's longest certified race of 3,100 miles, triathlons, and many ultra events in more than 30 nations. Includes news, photos, race information, library and links.
- http://www.srichinmoyraces.org

International Association of Ultra Runners
- Provides organizational information, newsletters, race listing and coming events, training tips, and links. English and Chinese versions.
- http://www.iau.org.tw/

Australian Ultra Runners' Association
- Seeks to promote ultramarathon running in Australia. Provides a race calendar, results, news, and links.
- http://www.coolrunning.com.au/ultra/

Extreme Ultrarunning
- Resources, links, and general information. Includes runners' profiles, calendar, photographs and race reports.
- http://www.extremeultrarunning.com/

New York Ultra Running
- Contains details about races in the area, highlights, pictures, directions, and membership details.
- http://www.newyorkultrarunning.org/

Ultrafit Endurance Sports
- Company that specializes in products designed for the endurance athlete.
- http://www.ultrafit-endurance.com/

UltraRunner.net
- Resource for clubs and races in North America with upcoming events, pictures, related links, mailing list and course descriptions.
- http://www.ultrarunner.net/

American Ultrarunning Association
- Membership details, race listing, USA National Ultra Team, description of the organization and related links.
- http://www.americanultra.org/

North Texas Trail Runners
- Information on trail running and ultra running in North Texas. Features calendar listings and a news/opinion section.
- http://www.nttr.org/

Hal Higdon: On The Run - Ultramarathon Training
- While focusing on the Comrades Marathon, author Higdon provides a training plan useful for a wide range of ultras.
- http://www.halhigdon.com/ultramarathon/ultramarathon2000.htm

Marathon and Beyond
- Published six times a year - website contains tables of content, sneak previews and ordering information.
- http://www.marathonandbeyond.com/

Stan Jensen's Ultramarathon Guide
- Provides general information on the sport, especially focusing on northern California. Includes information and statistics for the top races in the USA, as well as personal achievements, and goals.
- http://www.run100s.com