Make a marble run!
DIY marble run found on ohdeedoh.com
Here's another from Serving Pink Lemonade...
from Chalk in my Pocket
These silly face pillows would be an excellent craft to try!
via Ruffles and Stuff
DIY colored salt would make for a great afternoon craft project.
Create this Anti-boredom kit and break it out every time you hear "I'm bored."