Outlook conversation view and categories
Solution 1:
The best way I've found to aggregate several inboxes is to use color categories, rules and Search folders. The short version is you set rules that label your incoming mail into color categories based on if you need to get them done today, tomorrow, by next week and in 30 days. Then you create Search folders that show all email under each color. Everyday, you just go through the email and then triage them. This blog post goes even further. . .
http://blogs.msdn.com/b/ianpal/archive/2008/06/03/email-task-and-time-management-with-pifem.aspx