I've been using Digsby for about a week now since they opened their beta to the public and have to say I'm very impressed with it even though it's still in a relatively early stage of development.
At it's core it's a multi-protocol instant message client that supports all the big networks: ICQ, MSN, Jabber, Google Talk, Yahoo and AIM. It runs on Windows, Mac and Linux.
It also connects to most popular email systems notifying of new emails, including Hotmail, Yahoo, GMail, AOL plus any system that offers POP or IMAP connectivity.
So far so good but nothing radically different from the 101 other IM programs out there. Sure you get pop ups when new email arrives and the application ships with quite a few skins catering for most tastes.
Scratch beneath the surface and things are a bit different from most clients though. You can reply to messages directly within the popup messages. By using a central Digsby account, your Digsby settings are stored centrally and automatically update any version of the client you have logged in across multiple machines, no more repeating settings on multiple installs.
You can mark emails as read or report spam all from within Digsby too. But things get even better.
Digsby also has support for Facebook, Twitter and MySpace. Within the client you can keep track of updates from all your Facebook friends, keep tab of everyone's Tweets and MySpace updates too. You can also make updates to these networks too.
Finally Digsby has a widget you can place on your website or blog allowing people to communicate with you directly from the web.
The application is not without faults and does seem to be quite resource hungry using over 60MB of RAM and does have occasional slowdowns. But this is a beta so I expect things will improve over time. It runs adequately on my Eee PC though and does make life a lot easier by not having to run MSN, GTalk, a twitter client and a facebook plugin.
A full list of features can be found here: http://www.digsby.com/features.php
Overall I think this is a great app and is my new favourite IM client.
Overall rating 9 out of 10.