I save the stamps we receive on letters, and pass them on to "Sammy Stamp" (who use the proceeds from their sale for worthy causes). In the process, I've noticed that several of the Christmas cards we've received this year have stamps from previous years. One had a 2009 stamp (with an additional 5 cents) -
Several have a stamp from last year, including this one -
And of course many have had one of this year's stamps. There are several, but they include these -
Clearly people save their unused stamps to use the following, which displays commendable organisational ability!