I found this site yesterday, (actually my friend John sent me the link) and it's AMAZING (based on the tips on the first page).
The one that hit me the hardest was the one about organizing and cleaning up your Inbox. The tip is basically e-mail is one of three things, and that's the way you should group them in folders. That's it.... three folders.... if you need to find e-mails they say you should use a search instead of trying to group them. The one exception is GMail because it allows you to simply 'Tag' them delicious style, so it can be in multiple 'folders' at once.
What are these three folders? Check it out
I did this on my GMail account and my email account at work and already I'm loving it.
Now I'm going back through all the old posts and seeing what other tidbits of knowledge are buried here.