Siliconbeat in the threadlink above report on Citysearch's launch of their new Pay for Performance - Pay Per Call Ad service - Essentially, tracking calls aswell as clicks on the local search engine.

Less than a year old, pay-per-call is an alternative to the pay-per-click ad model popularized by Google and Overture. With pay-per-call, the merchant-advertiser only pays for its ad or listing after someone has picked up the phone and called them. Because phone calls are often considered better sales leads than someone clicking on your web site, advertisers will usually pay more for them, typically a few dollars per call. It's an ad model that's being marketed especially hard to local merchants.

Now if someone could just do that for affiliate merchants a lot of us would be very, very happy...