Randonneurs USA Describes the US branch of the randonneuring community, consisting of cyclists who attempt to qualify, through a series of brevets, for the ultimate Paris-Brest-Paris event (1200 km with a time limit of 90 hours), which takes place every four years.
Bicycle Calculators Compute speed, power, bike frame geometry, and a host of other specialized cycling functions
Crazy Guy on a Bike Non-commercial site devoted to bicycle touring journals. Close to 200 different journals are contained here now and you can create your own, too.
Sheldon Brown / HarrisCyclery.com Hundreds of pages on all aspects of bicycle maintenance. Technical information on older cycling technologies, as well as essays on proper fit, bike touring, tandems, family cycling, and our favorite, Real MAN Saddles.