Tumblr is growing--fast. The site's founder, David Karp posted Quantcast's latest figures on the Tumblr staff blog, saying that its 170 million worldwide visitors had propelled it into the top ten of U.S. blogs. And, like Zuckerberg before him, he pronounced himself "humbled" by the experience.
Tumblr's many gems include this and this. And you just know that this is going to spawn a Tumblr spin-off. When serious news organizations are getting in on the fun, and Tumblr becomes a place to shelter from the storm, you can see why it's shooting up the ranks.
[Images from that old chestnut Selleck Waterfall Sandwich]