Look at the people with smiling faces in the above illustration. It's not too difficult to figure out what's going on: it's their birthday, and they're all happy because they're about to get presents. What if they knew that you had totally spaced on the fact that they were celebrating the anniversary of their birth? Fortunately, there are plenty of services that will remind you of friends' and family members' DOBs, and Amazon is now joining their ranks with a Facebook-integrated program called Birthday Gift. The idea is simple: you can order an Amazon gift card for a Facebook friend ahead of time, and the company will make sure it gets delivered on their momentous day. What's more, you can also send invites to mutual friends to see if they want to pitch in a few bucks. This way, nobody feels terribly cheap for plunking down a couple dollars, and you won't settle for the standard Wall post birthday wish. Check out the video below to see how it all works.