I think Flattr (or something like it) has the potential to create a competitive economic system for digital goods. Traditionally, if you produce something of value, people will pay for it, and the content creator is rewarded. That model doesn't work well for digital goods, since they're nonrival (if you have an mp3, I can have it as well, with no loss to you) and nonexcludable (you can't stop people having the good, because you can't stop people copying bits).

Right now, digital content producers often have to support themselves with advertising, which is usually problematic or impossible. Advertising is kind of like a shitty version of Flattr where you automatically click the Flattr button by simply loading the page, and the amount each person donates per month is the average amount per capita that companies profit due to online advertising. It's a stupid system for a lot of reasons. The one thing it has going for it is that people take part whether they want to or not, by viewing pages and being affected by advertising.

Flattr might make creating digital goods a profitable activity -- and that's a critical to having an efficient economic system.