For the avid rock-climber or mountaineer, Estes Park offers a winter-pass-time of climbing ice-formations (such as icefalls, frozen waterfalls, & cliff/rock slabs covered with ice from water flows. The area surrounding Estes Park and within the Rocky Mountain National Park provides an abundance of alpine & water ice climbing opportunities.
For more information on ice climbing, equipment & techniques: http://en.wikipedia.org/wiki/Ice_climbing
For climbing equipment rental & guides:
Estes Park Mountain Shop: http://estesparkmountainshop.com/
Colorado Mountain School: http://www.totalclimbing.com/page.php
(Photo compliments of Estes Park Mountain Shop, http://estesparkmountainshop.com/)