My personal opinion? I'd keep all of that info under your hat. How much you pull in, server costs, all of it. There is always a noticeable change in the atmosphere when the specter of money is present.
It's absolutely amazing that a ton of users want to help out, carry their own weight and then some financially. If you make numbers public, then an act of community and altruism suddenly starts to feel like a burden.
In all honesty, the more that I think about it, the more I think the donation link should be at the bottom of the page, among the tutorial, tmi, and other links. It's less prominent, less conspicuous, and a whole lot more humble.
I'm sure others will disagree with me, but those are just my thoughts on the matter.