Summitpost.org
Great alpine information for routes and mountains all over the world. Summitpost has now grown into canyons, deserts, and some crags as well.
mountainproject.com
The best internet source for information on crags, boulders and big walls. Topos, route descriptions, photos, etc.
coloradomountaineering.blogspot.com
The internet blog/information site dedicated just to the mountains of Colorado.
14ers.com
The best website for beta and photos regarding the 14,000 mountains of Colorado.