If you're the outdoorsy type then you might enjoy tomorrow's free National Parks admission day. Over 100 national parks that normally charge an entrance fee will waive the requirement but let me say this: don't go!
Don't even think about going. I went with my family this summer and long story short they left me behind. Unfortunately for them I'm like one of those cool dogs from a Reader's Digest story and I walked all the way home in just under a week.