Hotmail now offers disposable email via aliases
Using an alias is handy for a couple of reasons. For one, an alias allows you to easily filter incoming mail. Register as a commenter on our site as firstname.lastname@example.org, configure a rule in Hotmail to handle messages sent to that address, and you're done. Want to register for a contest but don't want to be bothered after the deadline passes? Just turn off your alias, and mail sent to that alias will no longer reach your inbox. Unlike Gmail's email@example.com aliases, these are "real" email addresses -- so they'll work anywhere an address should (some sites don't like the + in normal aliases).
Aliases can be an incredibly useful feature, so it's well worth your time to learn a bit more about them. Head on over to the Inside Windows Live blog to read the Hotmail team's take.