US-centric: Next time you're on your way to the airport, you may be able to forgo printing out your boarding pass at home, opting instead to use your cell phone as your boarding pass. According to the New York Times:
At least half a dozen airlines in the United States currently allow customers to check in using their mobile devices, including American, Continental, Delta, Northwest, Southwest and Alaska. But so far, Continental is the only carrier in the United States to begin testing the electronic passes, allowing those travelers to pass through security and board the plane without handling a piece of paper.
So while this is currently a Continental-only practice (lucky Continental passengers), it bodes well for the rest of us as well. If anyone's been adventurous enough to try this out on a flight, let's hear how it worked for you in the comments.