There are museums for more than art. These topics give you a starting point for types of worldwide museums other than art. The links may bring you to actual museum websites or Wikipedia articles. Choose wisely.
These are two of the best sites for finding high quality images of artwork.
"...a gathering point for networked resources on Art and Architecture. The content is diverse and includes pointers to resources around the net as well as original materials submitted by librarians, artists, and art historians, etc..."
World-wide Art Museums online
Recommended by AP Central