With enthusem you can create branded note cards with whatever messaging you want. Inside the card is your copy plus a pick up code to get your attachment. The attachment can actually be a file - like if you were presenting at a conference and you wanted to offer the slides - or a specific url - you can direct people to a website, a blog, a promotion page, whatever you like.
I have had two experiences with enthusem, both interesting. The first was a card I received from Global Hugs Tour when I checked into my hotel for SOBCon at the beginning of May. It was a nice welcome card that directed me to the enthusem website where I entered a code printed into the card and was directed to a web page that gave highlighted the Global Hugs Tour project.
My second experience was when I received a card from the founder, Steve, after I followed him on Twitter (@enthusem). Instead of a generic DM, I got this card in the mail, which was much more personal and had more impact. It is more personal than a cookie cutter email and it provides a extra brand impression.
It costs $60 to send out 25 cards and $210 to send out 100. There are other amounts to which you can see on their site.
I highly recommend using enthusem as part of your offline and online communication strategy.