As good as the Microsoft Office suite is, some features could be better. Luckily, there's no shortage of add-ins to help fill in the gaps.
Of course, not all add-ins live up to their promises. But the following Office add-ins definitely deliver. They'll help you work more efficiently, and some of them will help you do things you might not otherwise be able to do.
Although Office 2007 and 2010 have improved search capabilities, you still might want to take a look at Everything, by VoidTools. Everything isn't a traditional add-in. Rather, it's an administrative tool that locates files and folders by filename. (It isn't limited to working with just Office.) You type in a search string, and Everything displays a list of matching files and folders. The response is almost instantaneous for normal systems. That's all it does, but it does it well. I don't even bother with the Office search tools anymore.