http://www.moma.org
This websites provides links for all types of art and art activities. It also has a link to another interesting art museum called PS1
http://www.metmuseum.org
This website is a great link for ancient art and has many resources for the classroom. The explore classroom portion is particularly interesting
http://www.nga.gov/education/classroom/
This website connects art and curriculum.
http://www.pbs.org/arts/arts_fineart.html
This portion of the PBS website is dedicated to helping teachers with ideas to bring fine arts into the classroom.