Here's a bit of fun for the runners out there - "Murphy's Law For Runners".
The Shut Up and Run blog highlighted this list that's been making the rounds, but it was supplemented by a few of the writer's own additions.
For example, the porta potty you select runs out of toilet paper. Or you think you're off to a great start in a race when you realize you haven't turned off the auto pause on your Garmin.
This is a fun read for any level of runner.