According to Ask.com, it analysed the subscriptions of the hundreds of thousands of users of its Bloglines service, which it acquired in February 2005, in order to create the index for its new Blog & Feed Search.

Bloglines is a free, Web-based RSS reader that people can use to subscribe to syndicated feeds from their favourite blogs. Ask.com had earlier said that it planned to integrate into its search engine features from Bloglines. The new Ask.com blog search index features about 1.5 billion posts and 2.5 million content feeds, as well as a sub-index of news articles from about 7,000 sites.

Ask.com says that by using Bloglines subscription data to populate its index, as opposed to the more traditional method of blindly sending a robot to crawl Web sites, it will be able to deliver more relevant and higher quality search results. In addition to factoring in how popular a blog is based on its Bloglines usage, Ask.com also mixes in its algorithmic search technology to solve queries.

The new service lets users search for actual posts, feeds or news, and sort the results by relevance, date or popularity. Right on the results list, Ask.com also lets users subscribe to feeds or clip a search result, both via drop-down menus located below each result. Ask.com gives users the option not only to subscribe or clip to the Bloglines service but also to other competing ones.

Meanwhile, the existing blog search engine in Bloglines has been improved as well with new features including the ability for users to search only within the blogs they subscribe to, or, conversely, excluding those blogs. The Bloglines search engine will also be able to recognize people's names and show posts by or about a particular person. Another feature is a list of the past hour's top queries, to clue users as to what is making waves in the blogosphere at any particular time.