Look2Skype - The Outlook Skype Add-In: "Look2Skype allows you to control Skype from within Microsoft Outlook 2000, XP, and 2003 on Windows 98, 2000, and XP.
Look2Skype toolbar gives you instant access to Skype features:
1. Make SkypeOut calls to contacts who don't have Skype installed or are not online.
2. Make Skype IP telephony calls to Skype contacts who are online.
3. Start Skype Instant Messenger chats to Skype contacts who are online."
Via Michael Sampson