Here are some excellent links for art-related sites.  This is a great place to familiarize yourself with contemporary and traditional artforms.

www.redbubble.com - This is a great site for ideas.  Mostly contemporary paintings and computer generated images.

www.wetcanvas.com - An excellent site to learn about different mediums and to see different art work in progress.  Great tutorials.  Also excellent picture reference materials.

www.metmuseum.org - The Metropolitan Museum of Art

www.moma.org - Museum of Modern Art

www.artsonia.com - A site to see high school (and elementary school) projects and artwork.

 www.arttalk.com - A site that offers information for every artist including links, tutorials, featured artists and more!