If you use GMail, here's an easy trick to increase the number of different email addresses that you have available: add periods to your address before the @ sign. Google will ignore the periods and forward the email to your primary address, but you'll be able to see the address to which the mail originated. For example, if you GMail address is myname@gmail.com, you could use addresses such as my.name@gmail.com, m.y.name@gmail.com, etc and they would all get forwarded to your primary address.