One of the coolest features in Office that I think many people (well, at least me) overlook is the translation capability. You can type in a word and get a translation immediately in any language you select. I'm currently trying to teach myself Spanish and find this feature really useful.
In most Office 2007 applications, you can find the translation feature on the Research pane in the Proofing group on the Review tab. In Outlook, right-click anywhere in the message body of an e-mail, and then click Translate on the shortcut menu.