Employment:

Summercampstaff.com - Summer camp jobs throughout the U.S. and Canada

General:

GORP - GORP.com is your encyclopedic resource for outdoor recreation—hiking, biking, rafting, camping, fishing, and more.
LNT - (Leave No Trace) The Leave No Trace Center for Outdoor Ethics is a national non-profit organization dedicated to promoting and inspiring responsible outdoor recreation.

Miscellaneous:

CampPage - A guide to Summer Camps and wilderness programs throughout the U.S. and Canada