As someone who does a lot of ordering, I can tell you that the packages I remember where the ones that included a hand written note, or something extra like a lollipop.
Recently, I ordered some DVD's from a company called Yes Video. Yes Video takes your VHS tapes, photos, Video Camera Cassettes and puts them onto DVD for you.
My family was very excited to receive the package since some of them where baby videos that we had never viewed. The DVD's were amazing but before we even got to them there was a Thank You label attached to a package of popcorn! How classy is that!? We would definitely watch the movies as a family and popcorn was the perfect addition. We were all thrilled to get this bag of popcorn that we could have purchased in any store but there it was conveniently in my movie box!
I will remember this company for the next batch of movies I send out and have already told 5 people in three days how great their service is.
The moral of this story is, it doesn't have to cost a lot to make an impression and taking a few moments to add that little something makes all the difference to whether the customer will remember you and more importantly, pass on your company's information.