I just got an email from "PayPal" with a link to Google AdSense. Might that be used to Click Fraud? The link looks very similiar to those you see in any Google AdSense advertisement.

It's against the TOS to that. You can report it to Google.

http://www.webpronews.com/insiderreports/searchinsider/wpn-49-20040331GoogleClarifiesNoAdSenseInEmail.html