I found out about a cool new trick from Lifehacker.com that seems to work on Gmail with no problems but not so sure about any other Provider as I have no time to check on it but thought it was cool enough to post about.

When signing up for a product (giving away your email address) you should now never give out your email address without adding that site to the Address.

• Instead of just entering username@gmail.com as your email, enter it as username+samplesitecom@gmail.com instead
• When Gmail sees a “+” in an email address, it uses all the characters to the left of the plus sign to know who to send it to. In this example it would still send it to username@gmail.com.
• If you search Gmail for username+samplesitecom, you will see all massages that were sent to that email address.
• To see who is responsible for sending a specific message click the Show Details link and you will see the complete address.

That’s awesome!