The free Outlook add-on Xobni beats the pants off Outlook's built-in e-mail search. While Xobni's core talent lays in rapidly finding e-mails and contacts based on any keyword search, it also excels at surfacing meetings and file attachments, hyperlinks, and even personal information extracted from social networks, like photos and phone numbers.
Visually, Xobni displays a sidebar that slides in an out from the right and over the reading pane. From there, you'll be able to search for contacts and messages, and interact with the profile, message, or files from there. When at rest, Xobni displays the profile it's collected on the contact in question--from a hyperlinked e-mail address and phone number to a Skype plug-in, Facebook picture, and LinkedIn profile, assuming the contact has enabled third-party sharing in his or her social network settings. You'll likewise be able to get at the contact's network, and past conversations from here.
Xobni also makes an appearance in the navigation ribbon of Outlook 2010, with a search bar and a shortcut key for hiding and revealing the side bar.
Activate the premium version, Xobni Plus, for $30 (and a free, 14-day trial) and you'll open the door to broader search data (appointments and tasks), more powerful search terms (phrases and Boolean), and an advanced search builder. Xobni Plus also includes full text and direct e-mail filters. Best yet, Xobni Plus adds its index of e-mail addresses to the "To" field of every message you compose, sometimes replicating, but nevertheless vastly expanding, your address book.
Unlike many other Outlook add-ons, both free and upgraded versions of Xobni add functionality without greatly dragging down Outlook's performance. The interface doesn't get in the way, and, in fact, makes communication easier. We recommend Xobni for any Outlook user.