I've always had this idea while going to college: Around finals week, everybody is always stressed out, incredibly busy, studying constantly, and worried about the exams and their overall grades. Well, I always thought about passing out free balloons in a free speech area or in front of our student union to kind of take the edge off a little bit. A kind word, some encouragement, a few smiles, and a free balloon could go a long way. And this idea doesn't have to be for college students during finals week only, it can be done at a local park for children, an ice cream shop, or anywhere really. The biggest concern would be following some environmentally safe guidelines.
http://www.balloonhq.com/faq/deco_releases.html This can help in instances of a bunch of balloons being let go, and floating away into forever.