Only problem with this is that a lot of people that dont have other email options want one adress for family and other trusted people. Changing that adress like you change socks does not work in the long run.
Well, when I sign up for anything I create an email account with that name I am signing up for, like travelocity@example.com. If I ever decide to stop using that service I can delete it and move on knowing I am unlikely to have more messages from them in any other account of mine.