With small stickers you will never lose anything anymore. You may put the address stickers on any smooth surface to make people aware that these things are yours. Like this everybody knows that CDs, books, DVDs or similar products you lend to somebody to whom they need to be returned. Furthermore the small address stickers are also handy to put on a letter in order not to need to write down your address by hand. In short, just remove the stickers from the sheet, put them on your letter and send it off.
The larger stickers can also be used with an own layout e.g. as label for jam jars. Like this you may give your little jam production to friends and family.