Matthew Cvetas a member of the Illinois Birders’ Forum created the following Google Maps for the state of Illinois.  It was a big project and should be useful to birders or anyone interested in exploring the great outdoors.
County
Maps of the Forest Preserve District access areas, trails, and facilities in northeast Illinois.
State
A list of state parks, natural, conservation, recreation, and fish and wildlife areas run by llinois Department of Natural Resources.
National
A list of Illinois outdoor areas administered by the National Forest Service, US Fish and Wildlife Service, and U.S. Army Corps of Engineers.