"Getting Things Done" (GTD) tells you that keeping your inbox empty reduces stress. I like that. However, continuously removing and filing incoming items requires effort, especially if you're getting lots of e-mail. I've been toying with an alternative solution lately; one where you don't have to actively file e-mails but still get the benefits from the GTD process.
My idea is that instead of your e-mail client opening the inbox by default, you instead go to a custom view with all your unread and starred/flagged messages. That way you will only see e-mails that are action items. By using this approach, e-mails will automatically disappear from the list as soon as you've opened them. If you need to follow up on an e-mail you simply star it and it will be visible in the start view until you remove that star.
GMail does not officially support saved searches, but there are simple ways to make this work. Basically you can save a search as a browser bookmark and then use that to open GMail. Bookmark GMail Action Items (drag and drop it to your bookmark menu) to save a GMail view of unread items in your inbox plus any starred items.
I tried to to something similar in Office 2007, but couldn't figure out how to write logical operators (and, or) for custom search folders. Anyone knows if that's possible?