Firefox 2 has a nifty feature for easily subscribing to RSS feeds in web based or desktop RSS readers via an orange RSS icon in the address bar when a feed is detected on a page. There's a good tutorial on this feature
here.
If your favourite RSS reader happens to be your livejournal friends list, then you can follow the above tutorial, using a uri value of:
http://www.livejournal.com/syn/?url=%s Here, I replaced the Yahoo reader entry to support LJ instead...
Note, you'll need to restart firefox after making the change
Of course, the usual restrictions apply, where only paid users can add a new feed, but with so many feeds already subscribed on LJ, there's a good chance that free users can make use of it too.