General:

GORP: http://www.gorp.com
REI: http://www.rei.com

Topozone (Topo Maps): http://www.topozone.com
Google Maps: http://maps.google.com
Highpointing: http://highpointers.org
Highpoint guides: http://americasroof.com
General Mountain Climbing: http://summitpost.com
National Parks: http://www.nps.gov

Regional Guides:
Colorado 14ers: http://www.14ers.com
Southern Utah/Northern AZ: http://zionnational-park.com