Except for the whole “make you sick and can’t be killed” thing, viruses are basically the ultimate renewable resource. They’re natural. They're numerous. They replicate themselves. And, after some tinkering by the Lawrence Berkeley National Laboratory, they can generate electricity.
A project at the lab has incorporated genetically modified viruses into a piezoelectric system -- a way of generating electricity based on touch. Piezoelectric systems exist already: They're behind the shoe- and pavement-generated electricity projects. But the current generation are made from ceramics, which create toxic byproducts. Viruses, by contrast, are environmentally friendly. The virus-based generator is five or 10 years from viability, but in the future the same organisms that give you the sniffles might also charge your phone.