It is the custom in Japan to send New Year's Greeting Cards which are like post cards. As long as you post them by the 28th of December, the Post Office will deliver them on New Year's Day. There are about three mail deliveries on New Year's Day in Japan, these are normally done by students who get a part time job with the Post Office during their winter school/college/university holidays.
We received a lot of post cards this year from friends, normally with their photo on it (often dressed up in a kimono). The three cards in this picture are ones we received from companies that we buy stuff from, another form of advertising I guess.
Note 28/06/2010: I've been adding more sub galleries to my Kansai sites gallery, as I plan to make it a comprehensive guide to the sites in the Kansai region of Japan (where I now reside). Hopefully this can be useful to people who are planning to come to Japan.