FeedLounge is another web-based feed reader service, that has gotten pretty stellar reviews, and has just opened up to the public. It has the requisite AJAXy interface, a full set of keyboard shortcuts, three different views (Outlook-style, three-column, or river of news), color-coded tagging and flagging, OPML import and export, 401 authentication, and more. One thing you'll find in FeedLounge that you won't in most other services, is a price tag: FeedLounge costs $5/month or $50/year. You can try a three-hour demo, but they only let 50 people on at a time, and the waiting list is pretty long.