I have inbox overload. I have too many email addresses. I'm on way too many listservs. The email from social network sites like LinkedIn, Twitter and Facebook only add to the inbox hassle.
I tried Xobni once. It slowed my Outlook to a crawl.
A friend of mine is using Boxbe. "Boxbe filters and prioritizes your email to reduce email overload. With an organized inbox, Boxbe makes it faster and easier to view, answer and send email. Boxbe is no-charge and integrates directly with Yahoo! Mail, Gmail, Google Apps and AOL Mail." I'm going to try it.
Any other apps that might help?