Professor Bruce Logan of Penn State University has got a cool YouTube show and tell on a microbial fuel cell. Flush your toilet; recharge your batteries. Could be a new way at looking at wastewater.
The technology behind microbial fuel cells dates back to the 1960s and the actual science goes farther back to the earliest decades of the 20th century. Today, there's a whole lot of research going into the making of microbial fuel cells. Very cool stuff. Professor Logan's got links to a great deal of information here.