SummitPost – A hearty archive hosting mountain route descriptions, and pictures for summits around the globe. It also features an active and targeted message board system.
Colorado Fourteener Initiative – A non-profit, volunteer organization dedicated to mitigating damage to and preserving Colorado's fourteeners.
FourteenerWorld Forum – A very active forum for Colorado's mountaineering community, featuring numerous trip reports and engaging discussion.
Colorado Mountaineering Accidents – John Kirk's excellent compendium of accidents in Colorado's high country.
Theron Welch's Mountaineering Website – Theron's is one of the finest trip report archives on the web. It's particularly notable for its information on Colorado's lightly-traveled Gore Range.
John Maki's Colorado 14ers – John Maki has some great pictures in his trip report archive, and he has a penchant for trying out some of the more challenging routes on the 14ers, like Quandary's west ridge.
Rex Headd's Climbing Site – Rex's site is another good one. For an epic, try his Gannett Peak report!
Brian Schultz's Trip Reports – Brian's a Minnesotan who's made the admirable accomplishment of climbing Colorado's mountains for 10 years while living 1000 miles away. Though he's completed the 14ers, Brian continues to come to Colorado to chip away at the centennial 13ers.
Doerzman Photography – Brent takes some of the nicest Colorado photos I've seen!
Gordon Novak's Rocky Mtn. Nat'l Park page – While limited in its scope to only RMNP, Novak posts some of the most beautiful pictures of Colorado mountains on the web. Be warned, the photos are large, and you could spend hours there!
National Weather Service – There's great information throughout the NWS website, or you can refer to our weather page for specific forecast zones.
Colorado Avalanche Information Center – Get the lowdown on avalanche conditions around the state. Active only during the long winter season of the mountains.
National Water and Climate Center snowpack maps – Quite useful for determining how much snowpack is accumulating and when. Good historic information, as well.
Highways of Colorado – I'm a bit of a road geek, too, my general enthusiasm for maps ultimately deriving from a road atlas obsession when I was in grade school. This site is jam packed with miscellany on Colorado's highways, including historical data on old routes.