I've been using digsby for quite some time now and don't know how I ever lived without it! Here's what digsby is:

1.) digsby is a multiprotocol IM client that lets you chat with all your friends on AIM, MSN, Yahoo, ICQ, Google Talk, and Jabber with one simple to manage buddy list.

2.) digsby is an email notification tool that alerts you of new email and lets you perform actions such as 'Delete' or 'Report Spam' with just one click.

3.) digsby is a social networking tool that alerts you of events like new messages and gives you a live Newsfeed of what your friends are up to.

The ability to have my IM clients aggregated into a single interface in key. Also, being able to see my Facebook, Twitter, gmail accounts, etc. all in one interface with alerting capabilities is something I value greatly.

The only problem is that it's not yet Mac compatible :o(. As a Mac enthusiast, I'm anxiously awaiting digsby to announce their Mac support ...