I subscribe to a service that lets me see how many people are visiting my site everyday, what countries they are coming from, their browser details, etc. For visitors that arrived via search engines, in about half of the cases the search engine will also pass along the exact search terms the person used to find my site.
On January 16 2012 at 12:53 AM Eastern time, someone in the Houston, TX area with Comcast Cable IP address 22.214.171.124 searched Google for "jeffs guestbook" and entered code into my guestbook designed to test for scripting vulnerabilities:
February 9, 2012:
... and a few more interesting search queries: