Browser Integrated Multi-Poster

You should give Yoono Browser Addon a try if you like to use Firefox or Chrome, and you like to be aware of your friends' activity at all times and/or regularly update any or all of the following Social Media accounts:

Facebook MySpace

Youtube Twitter

LinkedIn FriendFeed

Several IM's And more

What It Does For You

As you can see on the left hand side of the browser window in the picture a live activity feed of the platforms of your preference is inserted by Yoono.This allows you to follow live updates of your friends' activity on various platforms and easily multi-post updates. You have a choice of viewing all updates in a single screen or just IM's, social sites and updates in different tabs.
Here's a screenshot of the handy collapseable sidebar this adds to your browser window:

Evaluation

The only possible drawback is that if you have a slow connection or many friends on many networks it might slowdown browser performance too much for your liking. But you'll have to judge for yourself. Another feature that may annoy some is the little popup window for new updates of friends which can get in the way of using functionality in the same location on your screen sometimes.

Yoono also offers desktop and IPhone applications, so check them out at: http://www.yoono.com and try it yourself.