FriendFeed

FriendFeed is a service that makes it easy to share with friends online. It offers a fun and interactive way to discover and discuss information among friends.
Sign up for FriendFeed, invite some friends, and get an instant, customized feed made up of the content that your friends shared — from photos to interesting links and videos to messages just for you. And your friends get their customized feeds, full of the cool stuff that you've shared.

FriendFeed Notifier- Instant notifications and more:
Choose updates from your Home feed or any of your Friend lists
View, like and comment directly from the notification window
Drag the window to anywhere on your desktop