Idaho may be a state with relatively few people, but it certainly has a lot of counties! If you are researching family in Idaho, here are some mostly free resources for you.
FamilySearch Wiki – Idaho
Chronicling America – digitized images of Idaho historical newspapers
RAOGK – Genealogical & Historical Societies in Idaho Links to a long list. Scroll down to see them.
Boise State University – Special Collections & Archives
University of Idaho – Special Collections & Archives
Idaho State University – Digital Collections
Genealogy Societies
Historical Societies
Idaho State Historical Society – Searchable indexes
Idaho Falls Historical Society – with links to several other societies