If you're really bored, here's one way to amuse yourself in Outlook 2002 or earlier:
1. Start Outlook and turn off the preview pane (View | Preview Pane)
2. Select a folder with a lot of unread messages in it
3. Go to Tools | Options | Other | Preview Pane
4. Check "Mark messages as read in preview window", change the interval to 2 seconds, and OK out of all dialogs
5. View | Current View | Customize Current View
6. Click on the Filter button
7. On the "More Choices" tab, check "Only items that are unread"
8. OK out of all dialogs
9. Turn on the preview pane (View | Preview Pane)
10. Watch the items in the folder disappear every two seconds
P.S. This was fixed in Outlook 2003 (in order to make the 'unread items' search folder actually useful if you have the 'mark messages as read in reading pane' option enabled).