We have been using a bot under the name of the third party tool - mozenda. We are making some revisions to it and it will be called Ancestrybot.
Please feel free to add this to your robots.txt if you do not want your site included in the index. You can find more information here: http://www.robotstxt.org/robotstxt.html
Most website owners we have talked to are happy about this free service to help more people find their sites but we understand that not everyone will feel the same way.