MoMA (Museum of Modern Art) has a great new iPad app called Art Lab that kept my daughter and me delightfully occupied during a recent flight. You can sketch your own creations using cool tools and your fingertips while being inspired by the works of famous artists. My favorite is their version of exquisite corpse that two can play together. Use the app to create a sound composition, a shape poem, a group drawing and more. MoMA in real life has a very cool looking current exhibit called Century of the Child: Growing by Design 1900-2000 that also has a wonderful interactive website and tumblr site.
Field trip to NYC anyone? If you do go to MoMA with kids, be sure to check out their real life LAB where kids can have a hands-on art experience. A very kind security guard suggested the LAB to me after my then three year old son attempted to touch everything in the Museum.