First, it is relatively splog-free. Bloglines’ feed collection is based on user subscriptions, so any of the ~1M feeds in Bloglines collection are subscribed to by at least one registered Bloglines user. There are splogs in the collection of course (e.g., this and this), since nothing prevents a splogger (or his splogbot) from subscribing to each new splog. But, Bloglines knows how many subscribers each feed has and you can filter the results by requiring that each one have one, two or many subscribers.
Second, Bloglines has a high quality way of judging a feedâ€™s popularity. In general, ranking blogs is harder to do than ranking Web pages since the blogosphere is very dynamic and links to blogs are mediated for software infrastructure (e.g., Bloglines) and therefore completely or partially hidden. Moreover, there is much more of a temporal focus to search — users want to find yesterday’s posts rather than very popular posts from last year. (see tailrank for a good attempt to find hot recent posts). Bloglines has a stable based of over 100K users — big enough to use their collective subscriptions as the basis for feed popularity ranking. The only way undermine this is for sploggers and spammers to flood Bloglines with fake user registrations.
Bloglines indexes feeds of all kinds, not just those from blogs. This has advantages and disadvantages. On the plus side, sometimes you don’t care where the information comes from: news site, aggregators, community portals, data streams, or corporate blogs, personal diary blogs, etc. Also, there isn’t a clear line between the categories — is Slashdot a blog? The downside, of course, is that sometimes you do. If I want to find out what’s happening in Baghdad today, I probably want to search over news feeds and not MySpace diaries. Bloglines’s search does allow you to select between all feeds, just news feeds or all but news feeds. This is a good start.
Bloglines new search has some great advanced search features, too. You can restrict the search to posts and blogs to any combination of 20 different languages and also limit the search to a given time period.
We think Bloglines is a great service and their enhanced search system makes it even better.