This is a small collection of resources for people looking for non-academic jobs in ecology and environmental science
Ornithology Exchange Posts for positions related to ornithology, the scientific study of birds, or to avian conservation, management, education, or rehabilitation
Ecolog listserv An email listserv hosted by the Ecological Society of America, that includes job postings and other things
If you're looking for a job specifically in the Chicago area, some places that regularly hire undergraduate interns include Morton Arboretum, Chicago Botanic Garden, Field Museum, Lincoln Park Zoo, and various Forest Preserve districts (and Friends of the Forest Preserves)