Very nice!
I did a little group project in high school in which we had to make a short stop-motion film. Unfortunately, it's not on youtube.
But if I can find the DVD we put it on, I can try to upload it.
Ours involved an incredibly clumsy Lego ninja (voiced by me) being sent on a fool's errand by a pair of his friends to take on a castle full of knights single-handedly. Miraculously, his clumsiness led to him succeeding in this mission, although one knight (also voiced by me in my best fake Scottish accent ever) survived to chase him out of the castle at the very end. It took FOREVER to make, but we all had lots of fun doing it.
As far as ideas go, perhaps you could do something with objects found outside? Like rocks, leaves, and twigs, but have them be little characters going about their lives in the forest.
Just a thought, hehe.