Flattr

Flattr was founded to help people share money, not just content. Before Flattr, the only reasonable way to donate has been to use Paypal or other systems to send money to people. The threshold for this is quite high. People would just ignore the option to send.

When you're registered to flattr, you pay a small monthly fee. You set the amount yourself. At the end of the month, that fee is divided between all the things you flattered. You're always logged in to the account. That means that giving someone some flattr-love is just a button away.