Hippopost Lets You Send Free Postcards From Facebook

This looks pretty awesome, though I haven't tried it out yet.

Hippopost Lets You Send Free Postcards From Facebook: "Who says Facebook apps are useless? Hippopost has launched a new Facebook application that allows users to send their friends customized postcards free of charge. For now the service is limited to recipients in the United States and Canada, though we can expect the range to expand if Hippopost catches on."
-http://www.techcrunch.com/2008/06/16/hippopost-lets-you-send-free-postcards-from-facebook/