One of the pleasant things in my experience this summer commuting to work on my bicycle has been finding loose change and returnable soda/beer cans. One week I found $1.50 in quarters. So, not only am I saving money by not putting fuel in my car, I'm "making money" by riding my bike to work.
So, what have you found of value on your commute? Has anyone kept a record of how much they've found this year so far?