Tagged.com describe themselves as a "teen social networking destination on the web" but it is currently the largest source of email spam in our inbox.
Every other minute, there's a new email message from Tagged.com with a subject "[Your Friend Name] has tagged you! :)".
There's a link at the bottom of the email message that says "Click to unsubscribe" but even when you unsubscribe, "TaggedMail Invites" will continue to flood your inbox.
Though you can mark the email message as Spam, that won't affect Tagged since the message is sent using the email address of the person who has invited you.
Therefore, the possible solution is to block TaggedMail using a GMail filter and trash all the emails automatically. Here's one filter that you can use:
When a message arrives that has the words has Tagged you! :) in the subject and "unsubscribe from Tagged" in the message body, delete it. Simply blocking all email with the text Tagged.com may result in false positives.