30 Under 30 2011: Cool Companies' Apps

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Instagram, Kevin Systrom and Mike Krieger

If you've marveled at the aesthetic quality of a friend's photo album lately, you can likely credit Instagram. The free photo-sharing app has been downloaded by four million people who use it to add stylistic filters, frames, and effects to photos, which can—by tapping one of 16 options—turn a straightforward snapshot into what looks like a weathered Polaroid time-capsuled from 1977. Read more.