If you have the Gmail "Smartlabels" (or Smart Labels) lab enabled, the next time you log in, you'll see more options for automatically categorising your emails. New emails can be auto labelled as purchases, travel and finance -- in addition to the social, promotions, updates/notifications and forums labels already in place.
These new Smart Labels don't show up as new inbox tabs, the way the other smart labels do (at lest yet). They do appear, however, under the "Categories" section in the left menu. You can mark emails with these new labels in a new "Categorize this message as:" drop-down on messages Gmail thinks could apply.
As with the other labels, it looks like Gmail doesn't include emails that are archived in the Smart Labels section. While I'm still playing around with them, the Finance label seems pretty useful, and the others have a lot of potential too.