Flickr

Flickr started off life as an online game which incorporated sharing photos into it. But little did the creators of flickr know that it would turn out to be as big as it is today.
"Had we sat down and said, 'Let's start a photo application,' we would have failed," Caterina Fake says, a co-founder of Flickr . "We would have done all this research and done all the wrong things."
The game was never released though and in March 2004, Yahoo bought the company for an undisclosed fee and moved the 11 'Flickr' team members, with its company, from its home country, Canada , to the united States.
Flickr's traffic grew 448% to 3.4 million from December 2004 to December 2005, according to Internet measurement firm Nielsen/NetRatings. In the nearly 12 months since Yahoo purchased it, the site went from 250,000 registered users to more than 2 million.
Flickr is such a massive photo base, and has so mnany people using it world-widem, that in the last minute that i have been writing this blog, over 42,000 photos have been updated onto the website. The site has revoulutionised the way we use photo sharing.