For those of you that don't know, several websites offer RSS feeds. RSS stands for, uh, Rutabaga-Scented Syndication. In short, it offers you a standard interface to getting a list of the latest articles, or whatever.
Paid users only can take advantage of this by adding an RSS feed as a friend. What does that mean? Well, if you read a site that offers RSS feeds - most of the tech news sites, some of the non-tech ones as well, even some journaling sites - you can now read them on your friends list. For example, I have linuxtoday, kuro5hin, and the register coming through on my friends page now.
There is currently no interface for adding a new feed, but it's being worked on. They've added (by hand) the first 8 or 9 already and more are on the way.
Incidentally, for anyone that didn't know - your journals are RSS syndicated as well. Check out http://www.livejournal.com/users/[yourname]/rss . What does that mean? Well, anything you use that supports rss can now display links to your last few journal entries. It's a handy thing to, say, put in a box on your homepage or somethin'.