Free Address labels from Paralyzed Veterans of America--
http://www.pva.org/site/Survey?SURVE..._USER_REQUESTS
When you receive these, if you send a small donation occasionally (they usually ask for $3-$5 a couple of times a year...) they will keep you supplied with a nice variety of addy labels, holiday gift tags, a few note cards with blank insides, etc. You'll NEVER run out of addy labels again, and the small donations a couple of times a year support a great cause.
