Yahoo has expanded its "Buzz Up" content recommendation service to include many more publishers, stepping up its challenge against Digg.
Almost any publisher can now add a Buzz Up button to its Web site, Yahoo said. If a Web site doesn't have a button, users can also submit a link to the content via Yahoo.
Since its launch in February, Yahoo slowly built up the number of publishers participating in the service from 100 to 400. It has now opened it to almost any publisher -- although it said the service is "currently focussed on the U.S. only."
The change means that users will be able to "buzz up" more types of content, including the news, video and blogging sites that helped drive the popularity of Digg and similar sites such as Reddit and StumbleUpon.
Buzz Up has its own Web page, and Yahoo said some of the most popular content there could end up on its main home page.
Publishers can benefit from the "social content voting" because a less-trafficked site could see a surge in visits if an item is highlighted by enough visitors. That can mean more clicks or page views for advertisements, which increase a Web site's revenue.