There's an app for your junk... mail
The worst thing about junk mail is A) that it exists, and B) that they're always out of the half-price 60-gallon mayo jars by the time you actually get to Costco anyway. Now making junk mail exist-less, PaperKarma.
Developed by two Microsoft full-timers in their...er, part time, PK's a just-launched-on-pretty-much-every-smartphone app designed to reduce the approximately 800 pieces of junk mail that hit the average real mailbox each year, by instantly unsubscribing you from the most unwanted, including
advertising circulars, “pre-approved” credit card applications, telephone directories pretty much anything other than the Victoria's Secret catalog. Using PK's a two-step process -- first snap photos of your unwanted bulk mail, then tap "Unsubscribe Me", and the app does the rest: it'll identify and locate senders from a list they've compiled of the 10,000 or so biggest "junk-mail offenders", and automatically take you off their lists, something you want to be on even less than one featuring people who can be described exactly the same way, just without "mail" in the middle.
In the future PK may allow you to opt in to specific pieces from a certain sender, and will attempt to track down user-submitted junk-mailers that aren't already in their database with help from an Amazon developer's tool called Automated Turk, which apparently, unlike 60 gallons of half-price mayo, is something that actually exists.