Normally I'd never advocate going longer than 35 seconds without checking your iPhone for social news, Twitter favorites, or Facebook likes, but I'll definitely make an exception for UNICEF's Tap Project. The Tap Project is an initiative to provide clean water to children in need all over the world, and all you need in order to participate is your iPhone and mobile browser.
Head to the Tap Project page on your mobile browser (located at UNICEFTapProject.org) to start things up, and once you're ready to set your phone down for a bit you can activate the site's timer to begin. When you absolutely cannot stand to go another second without checking your Snapchat messages or Instagram profile, the site will tell you how much clean water you've helped to provide.
UNICEF is able to provide the resources thanks to sponsors who have pledged to fund the project based on the amount of time people can go without picking up their phones. And if you're thinking you can trick the site, think again; the web app uses your iPhone's accelerometer to make sure you're not just starting the timer and then tossing your smartphone in your pocket. No cheating!