So, how could we make money with tumblr blogs? So there are more ways.
Simple ads: Google Ads, Chikita
Just simply edit your site html (the google/chikita will give you a html code, paste this to the right html section [header probably])
From those, you will earn money when somebody click on your ad, or if you reach so many visitors a day, with an old blog you can earn great money, if you use your blog's html in the click-throught box, this will give you lot traffic.
Social Ads: Mylikes, Virulr, Buzzurl
They have ads for every nich, you can post to tumblr and twitter. The withdrawal rate is low (2$) so you can reach it fast, and you can earn money easily, but you must have a lot of clicks.
CPM (Impression ads)
Simply ads, but you will get money for traffic, easy way, just gather more traffic -> more money.
Advertise others site/blog
You won't get contact with any company, just with the other blogger/webmaster, it's great, nice money, but you can "use" this if you have enough followers, (probably 10k+)
Feel free to ask any questions in the comments.