As of now all vogella.de tutorials contain a flattr button.
Flattr is a mirco payment service which allows you to send money to free websites you like. If you are website producer you can put a flattr button on your website and also get flattered via flattr. 😉 With flattr you decide per month how much money you want to donate and if you like a website you just press the button. Your money will at the end of the month divided between the websites you liked.
I’m maintaining my website in my private time. If you like the content of vogella.de it would be great if you could support me via flattr.