University of Hawai'i
Jose Guadalupe Posada: My Mexico
This online exhibit from The University of Hawaii Art Gallery provides many images of Posada's woodcuts as well as insights into life in Mexico.
Arizona State University
Asu: Jose Guadalupe Posada: Calavera Revolucionaria
This site focuses on a single Posada work, "Calavera Revolucionaria." This web page also includes a link to a Posada biography.
Google Cultural Institute
Google Cultural Institute: Jose Guadalupe Posada
This visual website from Google Cultural Institute shares background information and photos about Jose Guadalupe Posada.