Xobni
With its hint of bubble gum visuals, Xobni is a free Outlook add-on that quickly searches through your e-mail. Just as Xobni's name comes from spelling 'in-box' backwards, so does its search philosophy, which is all about contacts. Finding contacts and message subjects routinely takes a fraction of Outlook's chugging.
Without ever using up more than three-quarters of the reading pane (and often much less when you collapse it,) Xobni can reply, forward, or open a message, or even a file. Its ability to throw in public information scraped from Facebook, Skype, LinkedIn, and Hoovers can add extra context. Dataheads will be intrigued by the stats analyzing your e-mail relationship with the contact, including the rank assigned to your most frequent correspondents. The analytics haven't figured much into my usage, but the Facebook pictures and quick-find searching do.
