There are so many little pieces of information in this world that prove to be puzzles to me at times, and I am sure that there are many for you as well.
For example, I knew underneath it all there was some sort of pattern to Zip codes - ones starting with 07 seemed to be in the New Jersey area, and I remember seeing Zip codes starting with 10 belonging to New York City.
Apparently, I am not the only crazy person who wonders about these things. Someone actually combined that curiosity with a Java applet that allows you to put in parts of a Zip code, and have it zoom in on where the Zip codes are associated with. It's fun to check out, or at least it was for me!
(This was on my mind because stamps are going up two cents on Monday of next week, 5/11/09: http://www.cnn.com/2009/US/02/11/stamp.increase/ - get "forever stamps" now!)