AOL will make some of its ad-banner space and partner sites' inventory up for bid in an online auction. Advertisers will be able to make cost-per-impression, cost-per-click, and cost-per-action bids. The good news for advertisers looking for cheaper alternatives in a tough economy — such as General Motors, which just announced it plans to cut online ad spending — is that the process will remove costly "friction" from the ad-buying process. The bad news for publishers: "Friction" is another word for "profit." Another concern: Allowing advertisers to buy space on their sites through ad networks will discourage them from developing relationshps with their highly paid salespeople.