Links
Thundertrail has a few great maps for the Colorado area. I used the one for Texas Creek and it was a great resource and was also very detailed and easy to use.
MapQuest is where all the road maps used at ATVTrails.org came from. Thier maps provide a great way to find your destination. I have also used their maps as trail maps.

Wildernet is the best web site I have found concerning outdoor news. This site also contains a lot of information on ATVing and Jeeping in Colorado.

These books are the best investment you could make in planning you off road adventure.
Trails Illustrated produces great maps that easy to use and have many trails listed on them.