ClearContext takes up residence in Outlook in the form of a sidebar (which replaces the older dashboard). At its core, it provides single-click filing and color-coding of e-mail messages and conversations. Version 5.1 adds a task organizer and project manager, both centered around e-mail. Take a look:
There's definitely a bit of a learning curve here, but a handful of ClearContext video tutorials (like the one above) should help you get up and running with minimal grief. And I suspect the new tools will prove indispensable to project managers. They're also a boon to the Getting Things Done crowd.
ClearContext 5.1 requires Windows XP, Vista, or 7 and Outlook 2003, 2007, or 2010. However, although it was free when we first wrote about it, the add-on now costs $89.95. On the plus side, there's a 30-day trial available.
By the way, don't confuse ClearContext with longtime favorite Xobni. The latter is more about searching e-mail and organizing/managing contacts.