It's interesting to see Tumblr described in many articles/forums as primarily for pornography. Tumblr has been the biggest user acquisition channel (and a free one, at that) for my startup, which has nothing to do with pornography.

We've gained tens of thousands of users in a few days from a single user post, and several user posts have accumulated 50,000+ notes. This is all thanks to the strong accessibility groups around ADHD and dyslexia that exist on Tumblr.

I've spent (wasted) time and money on FB ads, and I wish that I could have advertised on Tumblr. Unfortunately, every time I tried, they only wanted big brands with $25k minimum spend.