
WE HAVE A WINNER!!!
911, you guessed it! It's a mezuzah. Jewish people affix this to their doorpost. It contains a prayer scroll.
Ok, actually the parchment scroll inside is called the mezuzah, but a lot of people (including me) are in habit of calling the box a mezuzah. They come in many styles, from very decorative to rather plain.
Some info about them: http://en.wikipedia.org/wiki/Mezuzah
http://www.beingjewish.com/mitzvos/mezuzah.html
Good going, 911!! :-6