Use your watch as a compass

If you are lost without a compass, point the hour hand at the sun.  Halfway between the minute hand and the number 12 on your watch is South. 
A couple of pointers:
1. does not work with digital watches  (I just had too....)
2. hard to do if it's mid-day
3. your watch needs to be close to the correct time
4. fun to do even when you're not lost.  I had to go outside and check it out for myself...it works.