Random idea:
My email keeps filling up with "allowed spam" -- deals and coupons from B&N, Thriftbooks, and the worst of the lot, Michaels. All of these include a date, whether it be in the traditional 01/01/0001 format or Black Friday Only! It would improve my life (very slightly), make me happier with these businesses, and help me find relevant information much more quickly if these emails were just automatically deleted when they expire. After all, someone is going to be deleting these emails, and I'd rather it was the computer and not me.
Okay, Google, delete my spam.