By Michael V. Copeland

(Business 2.0) – The Web has changed the customer-acquisition game for those who sell everything from Hello Kitty lunch boxes to fine art. But--to the relief of those who sell Yellow Pages ads--it's done nothing for dentists, plumbers, or other small businesses that rely on phone calls for leads. San Francisco startup Ingenio aims to change that, and has finally landed a partner with enough traffic to take a piece of the dialing-for-dollars market. In late April, AOL will go live with Ingenio's pay-per-call service, in which advertisers fork up only when a customer dials the number listed in an online ad. If the service takes off, analysts expect Google and Yahoo to follow. -- MICHAEL V. COPELAND, GEOFF KEIGHLEY, AND OM MALIK