I've made a printable set of gift tags - the PDF is available to download for free here
These are so easy to make:
Print them out on 200gsm or higher card (you can find this at your local stationery shop). If you don't have a printer at home you can take the file to a copy shop and they will be able to print them for you.
Cut the tags out just inside the dotted line
Punch a hole in the top of the hat
Loop a length of string or bakers twine through the hole
Write your note on the back and then attach to your presents!