Oversized Postcards, Rack Cards
Business Cards with blank backsides.
I love vistaprint.com. You can sign up to get their emails and they will offer lots of "free" products that you just have to pay shipping on. I usually end up paying a little to get envelopes and to have blank backsides on the business cards. BUT I use these all the time. They are easy to tape to a package or punch a hole in the corner and attach to a gift bag.