Seriously Useful Privacy Tool
Many free websites (like newspapers and forums) require an email address to sign up. To make sure you give them a real one, they send you a password or activation code, usually within 60 seconds, by email.
Guerrilla Mail will issue you an email address that is good for 15 minutes. You don't even have to leave the web site, just hit refresh and any emails you receive show up there on the screen and can even be replied to. The only problem is that this will leave you with an impossible list of user ID's, but it is great for, say, forums where I only need to post one time (say with a customer support question).
Via this list, via Tom Kirkendall
