Flattr is the "worlds first social micro-payment system", as they say. But it's also a bit more.
It's a convenient way to support the work of the people you like. So I just added a flattr button for Studio AMANgA on each app's web site.
Of course I don't want to try to convince you of anything, but I think it's a very nice thing for everyone around here, on the internet. And once you have an account, there's no limit to the number of projects you can support, so feel free to flattr.