You may have to click on something or change settings to activate Flash for these. They will probably not work on iPads.
Mondrimat - Make your own Mondrian drawing
Haring Kids Games- Based on art by Keith Haring -- also see interactive coloring book.
Mr. Picassohead - RFI Studios
Street Art - Tate Gallery, London
Art Parts - Tate Gallery, London
Destination Modern Art - MoMA, New York
Requires Flash 8