Here are a few of my favorite art related links:

World of Watercolor  One of the best of the best. Beautifully organized.  After you get done
                                              looking around you can spend several more days following all their links!

Watercolor Online  Another nice site with a weekly "featured artist".

Wet Canvas  A good site for basic instruction in all sorts of media!

Windsor & Newton  A lot to see here.  Some good beginning instruction.

Native American Art A place to see some beautiful art by Native Americans.

There are also many great sites offering art supplies for sale online.  I will add these links soon!