Christmas Trees and Sukkahs

I just received an email from the chaplain at our co-located Air Force Base, which contained an interesting bit of trivia:

Unlike our Christian brothers and sisters who are not permitted to have a Christmas tree in the Mall here at the base, we, in fact, are permitted to have a Sukkah. Why? Because for Jews, eating in a Sukkah during Sukkot falls under the category of “religious obligation.” It is a commandment for all Jews to “dwell” in the Sukkah at this time.

I find this fascinating, and just had to share it. I wonder if there are other such obligations (or how the religious right would take this if they figured it out).