A splendidly humourous post here on Instructables.com, with the author asking for interesting possible uses of old batteries!

A few useful suggestions were raised in the comments to the post:

“if they are AA put a few layers of duct tape and shoot them out of an air cannon”.

Great idea! Although not that constructive, it may be said…

A second answer:

“Stack them artistically on top of your dad’s classic Porche so that the acid trails from the leaking batteries make interesting patterns of corrosion down the sides of the car.”

Entertaining, but also not that useful…

There was a blog post on thegoalkeeperco.com recently about some goalkeeper gloves that were going to be created with battery power in them – another interesting use! The idea is supposed to be using batteries in the gloves, in order to power flashing lights and deter or distract opposing players! Now that is an invention that would be fun to see!

Almost as good as this solar powered hat…