I like a good science project like the lemon battery. It puts a smile on my face.

I saw a video on YouTube a few days ago involving an onion, some gatorade and an iPod. Based on what I know of the science involved, I don't put a lot of stock in it being true, but it's at least entertaining.

A lemon cell battery is made with a lemon and two metallic electrodes of different metals such as a copper penny or a copper plating. In practice, a single lemon cell is incapable of lighting a light bulb; one would need about 500 lemons wired in parallel to light a standard flashlight bulb.