Snopes is a great site that confirms or debunks many of the internet and email stories out there.
This is a great site to use to confirm that email you got the other day about a Pepsi driver, or about Microsoft giving away money if you forward that email. They also have information on my web hoaxes and bad web sites. They do a great job researching the rumor or email and post the evidence they have confirming or denying the rumor.
Use it with your students to show them how not everything on the internet or email is true.