3 links
Hydrangeas Plus
hydrangeasplus.com
Oregon nursery specializing in a large selection of species and cultivars of hydrangea. Includes images and information.
Nantucket Hydrangea & Hydrangea Farm Nursery
nantuckethydrangea.com
Offers and extensive listing of hydrangea cultivars. Many varieties, a few pictures.
Wilkerson Mill Gardens
hydrangea.com
Specializing in hydrangeas and offering a selection of other shrubs and some trees.