Sneakemail is a free service
that you can use to generate disposable email addresses
From their website
These "sneak email" addresses are aliases of your real address, which is kept hidden.
You can enter these Sneakemail addresses into web forms or
use them to contact e-businesses without the risk of your real address being abused or bought and sold.
Consider each Sneakemail address as an informal agreement between you and an online business or organization.
You agree to allow them to contact you through this address,
and they in turn, by accepting and using this address, agree not to abuse this privilege by sending you unwanted solicitations or to give or sell your address to others.
The best way to understand Sneakemail, if you don't know the technology involved, is with a telephone analogy.
Imagine you discovered that, due to a technical error, the phone company freely gave you a new phone number whenever you asked and didn't revoke the previous number. If you kept asking you would accumulate a bunch of phone numbers that all went to your one phone line. You realized that, if you could find a phone that showed the number somebody was using to call you (reverse-caller-id?) you could do something very useful.
Every time you needed to fill out a credit card application, or a store clerk asks for your phone number, you would give out a unique phone number obtained just for that purpose. That way, if you start getting calls from telemarketers at that particular number you could call up the phone company and tell them to disconnect it. Not only do you succeed in stopping the annoying calls, but you know who gave them your number.
Sneakemail works just like an unlimited supply of phone numbers and a "reverse-caller-id" phone, except, of course, the phone numbers are sneakemail addresses, which you can create freely, and the special phone is your inbox.
http://www.sneakemail.com - Neat.