Massive Enumeration Toolset
Massive Enumeration Toolset (MET) is a collection of Python scripts designed to perform various passive information gathering attacks which can be useful when evaluating the security of public computer networks.
MET is constantly changing. There is a high chance that the latest version is not working in some situations. The problem is due to the fact that MSN, Google and other search engine vendors change the format of their results pages every so often. This means that sometimes you may need to modify the hardcoded regular expressions a bit to make the tool work.
UPDATE 2011/07/20: this project is unmaintained so you have the opportunity to take the lead. Let us know if you feel inspired.