trawlr is a web-based RSS aggregator that offers a tonne of features, and, best of all, has PostRank built in! You can use trawlr as an RSS reader to manage your existing feeds; it offers OPML importing and plenty of subscription management options. You can also create a lifestream, bringing many of your online activities — del.icio.us, flickr, last.fm, etc. — together in one place.
trawlr is also a great discovery engine. Browse all feeds that users have added. Explore topics using the tags that users have added to their feeds. Use the trawlr spy to see the most recently added or favourite-marked items.
The interface and functionality are clean and simple, and really streamline information management. Use the built-in PostRank filtering to tweak your feeds or feeds others have submitted for relevance, from “all” to “best”. View the rankings of recent items in a feed you’ve subscribed to and get an idea of the relevance of a site’s material. Create customized RSS feeds of your favourites.
trawlr works with Internet Explorer, Firefox, and Safari, and, of course, offers an iPhone-optimized version for info management on the go. A simply fantastic Rails-powered, one-man effort. Great work, Ben!