Digsby provides you with IM, email and Social networks in one easy to use application.
Instant Messaging - 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.
Email Notifications - Digsby is an email notification tool [...]

Keep friends at your fingertips with the new Yahoo! Messenger:

Easier ways to stay up to date - See more updates from your friends in the detailed Messenger list
Show off your status - Easily add links and emoticons to your status messages
Watch videos together - Share videos from popular sites and watch them with friends right [...]

Miranda IM is a multi-protocol instant messenger client for Windows. Miranda IM uses very little memory and is extremely fast. It requires no installation and can be fitted on a single floppy disc. Its powerful plugin system makes Miranda IM very flexible. Only the most basic features are built in, but there are currently more [...]

Gizmo is a Free Phone For Your Computer that makes calling as easy as instant messaging. It includes these features and more:

Voice Calls - Call anyone in the world for free from your computer, save big on calls from your mobile phone.
Instant Message - Chat with friends on Gizmo5, MSN, AIM, Yahoo! and Jabber for [...]

Thunderbird is a great email client from the same people who brought you the Firefox browser.
Thunderbird gives you IMAP/POP support, a built-in RSS reader, support for HTML mail, powerful quick search, saved search folders, advanced message filtering, message grouping, labels, return receipts, smart address book LDAP address completion, import tools, and the ability to manage [...]