Dunkirk Dave's Groundhog Haven: Information about groundhog Dunkirk Dave and other groundhogs in captivity and in the wild; links to other groundhog sites.
FactMonster: Groundhog Day: Offers a simple history of the observance.
Fermilab Woodchucks: Fermilab, in Illinois, has woodchucks (also known as groundhogs) that live happily on the lab's 6,800 acres.
Groundhog Day History: From the official Punxsutawney, Pennsylvania web site.
Groundhog Day History: With folklore and winter weatherlore, from stormfax.com.
Groundhog.org History: History of Groundhog Day, and a list of Punxsutawney Phil's predictions since 1887.
Groundhogs at HogHaven: Learn all about a colony of groundhogs that live in Delaware.
Wiarton Willie: Canada's answer to Punxsutawney Phil.