Flattr is a way for you to show your appreciation to content authors with your money.
For example, if you like my IntelliJ theme from a couple days ago, you could have clicked the “flattr” button and it would have assigned a piece of your monthly flattr allowance to me. Or if you enjoyed one of my videos on pv3d/robotlegs/signals etc, you could encourage me to make more by clicking on the flattr button.
It’s been in beta for a while, but I think you can still sign-up here: flatter beta sign-up
I’ve never been a fan of ads of any kind (although I still like recommending books through that amazon partnership program), but I think flattr is a simple, straight-forward, you-know-what-you’re-getting-into program. For example, I can say, “If you liked this video, please click the flattr button!” Whereas I could never do that blatant request for support with ads.
Anyway, the little flattr icon will be floating around the bottom of my posts from here on out, so feel free to click it if I’ve ever helped you in any way ;)