We run a couple of "Local Sponsored Listings" on Yell.com. In order to find out how they are doing (i.e number of impressions and clicks) we have to telephone Yell and ask them. How ridiculous is that? (Although even providing performance data is a major step forward for Yell, they didn't even used to do that a year or so ago). Surely any web-based advertiser should be putting that on a website to be retrieved by customers on demand.
The performance of those listings is predictably dire, costing roughly TEN TIMES what we pay for a click on Google Adwords. Why is it so expensive? Presumably because Yell has to fund a call-centre of people reading out performance statistics over the telephone; plus pay an army of over-zealous but usually ill-informed salespeople. Google has neither of those functions, plus is quietly building up a database of local businesses so it can (presumably) go head-to-head with Yell on local classified advertising. Once Google get themselves ready, I'd give Yell.com 12-24 months to survive. You read it here first.