I've long been a Google Reader and Google Reader shared items link blog advocate. The service lets me call out to you what I'm reading in the blogosphere, and what I find interesting. But for me, and for many other people using a wide variety of Web 2.0 applications, my link blog only covers one facet of my activity.
Where Google leaves off, Friendfeed steps in, combining my updates from around the Web, not only from Google Reader, but also noting when I update louisgray.com, when I add new items to del.icio.us, when I Digg new stories, find something via StumbleUpon or add photos to Flickr. Others also use it to display their activity on Twitter and Pownce. This creates a feed for not just one facet of my activity, but many.
That answers the "feed" portion of Friend feed. But the "Friend" portion takes the service up a notch. I can subscribe to friends and watch their activity one by one, or go to a combined "Friends Feed" and see all their combined activity. From this page, I can see if MG Siegler Dugg a story, if Fred Wilson added a new post to his blog, or if Jeremy Zawodny added a new bookmark to his del.icio.us items. It's a lot like reading Robert Scoble's shared link blog, but one written by multiple people, and with more sources.
The site is currently in beta, and ramping up, having been started by a few notable ex-Googlers, looking to gain traction as the service goes viral. Their blog shows their new office space, as they're just getting started.
My feed is here. If you need an invitation to the service, just say so in the comments, and I'll send it via e-mail.