Karp has made a website that has collected $85 million in funding last fall despite having no discernible revenue mechanism, is unabashedly promoting its creative platform as the ideal place for brands to show off what they've got.
Starting Wednesday, the five-year-old microblogging platform will begin posting ads in the curated “Radar” post section of Tumblr users' dashboards, which Karp says gets 120 million impressions every day. Ads will also be featured in a section called Tumblr Spotlight.
Karp says Tumblr—where "the core of our community is millions of people making things"—is, in fact, an ideal place for advertising, especially when you consider other social-media options such as Twitter or Facebook, which have (thus far, anyway) been pretty limited with the scope of their advertising.
“The means for targeting [consumers] is anything but creative,” Karp said, pointing out that while Twitter is limited to 140 characters and Google won't help a band "sell out their show," Tumblr can use images, links, and video in its advertising to help brands, musicians, and others promote themselves.
http://techcrunch.com/2011/02/22/founder-stories-karp-tumblr-making-money/
