A high-rep user normally invests a significant amount of time at SO, and normally contributes with awesome questions & answers. I frequently see extremely good content and I think the effort put into that could also be rewarded in the form of donations. Correct, money donations.
The original idea is not to monetize the site. The donation would go straight to the respective author. Besides Jon Skeet, nobody would get rich from these donations, but I think it would be a great form of recompense. Integrating a payment service into the current system shouldn't be toilsome. Take PayPal as an example - all you need is a visible link for each answer whose author informed a PayPal account.
Well, I won't elaborate any further because at this point you might think I'm insane. What are your thoughts?
NOTE: Found an interesting question regarding donations, but the goal is different than what I'm proposing here - Add a paypal link to accept donations?
UPDATE: Donation is optional, and donor and receiver must not be published. You could donate to whoever you wish, whenever you wish, for any reason you wish. IMO people are unlikely to fight over donations if they don't know who is donating to whom, and when. Moreover, the only difference in having a link for donation in your profile versus in each of your answers, is the visibility.