Donations - Put your money where your mouth is

Dear Khan Academy Team,

I'd love to donate for the development of Khan Academy, but like anyone, I have my own individual purposes to use it. That means that for me, a variety of topics on Khan are not of interest while others definitively are.

For instance, I really need to gain a better understanding of differential equations. However, in my opinion, the differential equation section really needs some brushing up / improved videos. That's why I would like to be able to donate for a specific purpose on Khan Academy.

I have seen this concept on other webpages, where they let the donators indicate what they want the company to do by deciding how much of their donation should go to which area of development.

So, can't you come up with a "put your money where your mouth is" kind of donation process where donators can, for instance, decide, "I'll donate $X for the development of..." (followed by html radio buttons with topic titles, or sth. of that sort)?

I'd appreciate if you could give this idea some consideration. I'd argue that this would also be an exceptional way to find out the true wishes of the users, because nothing delivers a more reliable insight into customer intent than an actual purchase - or in this case donation - decision (as opposed to making surveys where the market researchers merely ask for opinions).

Many thx and greetings,

Rob.