Dogster brought us a story this morning about a Cambridge, Mass. dog park that has invented a Park Spark, which is a way to convert dog poop into energy to power a light. Basically, everyone picks up their dogs poo in a biodegradable bag and deposits it into a feeding tube then turns a hand crank to allow the methane to rise to the top and provide the spark in the lamp to provide light for the park. This is a great way to be green and I think probably encourages people to pick up the poo! The best thing is that all the patrons of this dog park now have light at night to see by (so long as you stand by the lamp).
I encourage you all to look at the Dogster Blog, it goes into much more detail than I have here and there are a couple of diagrams to help explain the usage.
To view the Dogster Blog, bark on the link: Bark!