Here are a few resources that I found to be useful.
Resources:
http://www.4kids.org/servlet/coolspots.SearchCoolspotsByCategory?categoryId=9&catName=Art+and+Music&subcategoryId=165&subcatName=Virtual+Museums
http://www.artcyclopedia.com
http://www.artedia.org/links.html
http://www.arteducators.org
http://www.educationworld.com/arts/
http://www.getty.edu/education/teachers/index.html
http://www.meetthemasters.com/how-it-works/
http://www.metmuseum.org/learn/for-educators
http://www.philamuseum.org/education/lesson_plans.html
http://www.artcyclopedia.com
http://www.artedia.org/links.html
http://www.arteducators.org
http://www.educationworld.com/arts/
http://www.getty.edu/education/teachers/index.html
http://www.meetthemasters.com/how-it-works/
http://www.metmuseum.org/learn/for-educators
http://www.philamuseum.org/education/lesson_plans.html