A dynamic website featuring many of Philadelphia's famous murals, including this one, "New Fire/Fuego Nuevo" by César Viveros-Herrera.
Institute for Latino Studies Oral History Project
Digital archive of interviews with Latino artists - a great primary resource
Calisphere
SPARC
The Los Angeles-based Social and Public Art Resource Center (SPARC) is an arts center that produces, preserves and conducts educational programs about community based public art works.
Espacio Zapata
See what contemporary Mexican artists are producing in the way of murals, prints, posters, and installations. The Espacio Zapata is a gallery representing the work of the ASARO collective (political art collective based in Oaxaca) and many others.
Library of Congress Print and Photographs Collection
Try a search for José Guadalupe Posada to see other works by the famous Mexican artist:
Latin American Network Information Center (LANIC)
A web-based, scholarly resource for finding information related to Latin America. Some links may be broken, but in general it offers a wealth of information.