If you use the many popular social networking sites, such as Facebook, Flickr, Twitter and Digg, you might want to give Flock a try. Flock is powered by Firefox, so you may think it’s similar or even the same, but it isn’t. There are many things in Flock that make your social network life easier. You can reach friends over multiple networks without having each website open, check your email and share photos, videos, text and favorite links to your friends. You can also be notified when a friend updates, site notifications and when your favorite websites update.
Flock caters to a bunch of web user types. I think the people at Flock describe the user types pretty well in this link – Getting Started in Flock. Flock is available for Windows, Mac and Linux versions.