[moe]

I've said it before, I think they should just get one sponsor per year and be done with it.

Just stick a permanent "Powered by Coca Cola|Microsoft|Whatever" banner in the footer; Coca Cola and friends surely won't mind to cover the operational costs of Wikipedia (and then some) in return.

In order to prevent a sponsor from becoming too influential they can simply make it a rule that the sponsor must be cycled annually. They could even have the community vote on the sponsor for the next year.

Sponsors would certainly wait in line for this ad-spot and personally I'd prefer it over the constant begging on every page.