Since I enabled Gmail Smart Labels my inbox now has 50% less email and tied with the priority inbox I only see the most important emails.
The labs addon most useful feature is for bulk email - anything Gmail categorises as a newsletter is given the bulk label and skips your inbox allowing you to browse these emails at your own convenience.
"Automatically categorises incoming Bulk, Notification or Forum messages. Filters are created to label mail with these categories and Bulk is filtered out of the Inbox by default. Use Settings -> Filters to modify these defaults or create new filters. Report miscategorised email from the 'Reply' drop-down menu."
You can enable Smart Labels from the Google labs tab of the Gmail settings page.