You were downvoted for adding a snidey remark to a decent question. Next time just ask the question. Since I'm curious as well, how does Tumblr make money besides themes? Does anyone know their monetization strategy?
Yeah, sorry I forgot Hacker News was all srs bznss where no humor is tolerated whatsoever.
On the Tumblr monetization front, TheStartupist[1] covers a good portion of their story. Checking Crunchbase[2] shows that they've gone through pretty large funding rounds, with their last one (D) at $30M the largest. I've been trolling Tumblr for the last year and half, and the only things I've been able to scrounge are the $9 Directory listing under your category of choice and the premium themes.
They're still growing massively, as all the cool kids congregate there to post their Instagram-faded pics of teenage angst, but are hemorrhaging money like Twitter. And like Twitter, advertising is viewed as pure evil[3] and not a viable solution to generate revenue. Twitter realized the inevitable and started Promoted Tweets recently, and Tumblr will have to do something similar soon as well. Maybe they make enough from the themes, but that seems a little quixotic.
Meta: I come to HN not because it is a logical syllogism server but because it often has thoughtful, interesting comments. I own a couple of single speed bikes--for all we know shii does too--and I didn't get offended by his comments. While I'm against viciously abusive attacks on people, I think there's a danger in trying to create a Disney World like atmosphere where no one poops or says things more caustic than "gosh."