WARNING: don't read this post unless you have a good chunk of time to invest, because once you start looking at these images it will be very hard to stop.
You will find them both inspirational and motivational.
National Geographic has published their "Best of" list in several different categories, and here are the links to all of them:
The best of pictures of the day.
Best of 2012 - National Geographic Magazine Photos.
National Geographic Traveler 2012 photo contest.
Enjoy them all, I sure did.