A few weeks ago, I entered this small design competition with a group of friends. I was responsible for the prototype. Essentially, we had to design a mechanism for green bins (you know, those bins you place outside your house filled with garbage). Thing is, the garbage is actually an all-you-can-eat buffet for prowling masked rodents - a.k.a. racoons - at night. So the mechanism had to be designed in a way which would prevent racoons from creating a mess on your front lawn by toppling over your green bin, and spilling the contents. Interesting problem, I suppose.
Read more here: http://www.treehouseprojects.ca/electrobin