Crookes Radiometer

• $9.11
• Amazon.com

A Friend once gave me one of these, and I kept it in my office. With the move to the new office, I bought seven of them - one for every window - and now we have a little factory of solar windmills churning away on bright days.

Half toy and half science experiment, I think these are great little living features for a home or office. You can read all about them here.