StrangeSearch is a free, open-source indexing and search engine for Windows by Jeremy Davis and Dan Dunham.
It was originally developed at Iowa State University and is the inspiration of several search engines.
It has native Windows user interface for administration and is accessed through a web browser for searching.
StrangeSearch has the ability to index the files shared by a large number of computers on a network via FTP or SMB (Windows file sharing).
It also has a basic web interface pre-built in Perl to allow for searching and ranking of the top shares.