Instagram is a free iPhone application that serves as a photo editor and social sharing tool. When you take a picture, you can change the image properties so it has a different color hue or a different frame. Then you can share the edited image on Facebook, Twitter, Tumblr, Flickr, and Foursquare. If Instagram actually has one million users as of right now, then that means that 500,000 people signed up in 19 days. Not bad considering that Andreessen Horowitz decided to invest in Picplz instead Instagram after evaulation. [Scobleizer]
