Flattr

''Creators register their site with Flattr and embed a brown-and-yellow icon on each page, similar to a Facebook "like" button. If you enjoy a video you can "flatter" it by clicking the icon. Payers have to prefund a Flattr account monthly, but that could be as low as $3. At month's end a payer's funds are divided among those they've flattered. Flattr takes 10% of the money received by content creators.'' [source]
''Flattr Moves Micropayment Concept Forward - but History Bodes Poorly'' [source]
''Getting Past The Hurdles Of Micropayments'' [source]

Technically, this is how it works: [page], and [here]