Quite a few people would donate for Firefox development, but they can't donate to Mozilla because Mozilla spends the money on other stuff. Until now, as Google's lapdog, Mozilla didn't need donations, so that wasn't a problem (for Mozilla, it did however result in firefox getting 2.62% market share).
To reinforce this, I'm a stingy bastard but I'd give them 5$ a month if I could donate them to the browser development itself since it's the program I use the most.
