To promote their Gmail service, Google is offering the chance for anyone to send a single free postcard to any US address, no strings attached. Obviously being in Canada, this isn't as handy but you can still send it to someone you know in the US (or if you don't know anyone, why not drop Barack Obama a quick note? Or some of the people in the MetaFilter thread where I first heard about this are planning to send it to politicians to either compliment or condemn some of their recent activities.)