You have probably heard of lemons being used to run simple digital watches back in 1980s, fun but probably no real life use for citrus fruits as means to run gadgets.

But today in seems vegetables have uses instead, this time for lighting (LED technologies have massively get better in last couple of years)

Perfect for developing nations where batteries are scarce and expensive, not to mention poisonous at the end of the lifespan, and yes its those darned clever Israelis again that came up with the idea of using the humble spud.

http://www.engadget.com/2010/06/20/yissum-develops-potato-powered-batteries-for-the-developing-worl/

The article doesn’t say when your potatoes need to be changed, or if when they grow shoots if that affects their performance though.  Imagine this conversation one day:  “Hello, yeah, er I can I call you back in a couple of hours, phone battery is dying and I need to get a kilo of King Edwards from the market, speak at 9pm mate, bye”