Geohashing

Let's go with XKCD again to finish out the year and promote a new hobby: Geohashing.  Randall Munroe hinted at this pastime earlier in a Christmas-themed comic, but this time thoroughly threshed it out into a full-blown instructional, complete with interactive website.  I was going to try to determine whether the geohashing algorithm had any pattern or if it was fairly random, but somebody already did that here:
http://wiki.xkcd.com/geohashing/The_Algorithm#Randomness

... which led to this next discovery: Did you know that geohashing has its own wiki?

Here's another odd hobby XKCD has originated:  http://xkcd.com/249/, photos of people doing it: http://xkcd.com/chesscoaster/

By the way, the secret text that is revealed by hovering over the cartoon on the xkcd site is:

Saturday is game night.