Ediscovery software, and I used a bespoke solution in that job, takes a job that can take weeks or months the and makes it possible to do it in days. Or y'know, you could use a filing system and do it in minutes?

or you know could spend 0 pence on something and just organise your folders

also IIRC Windows Index Server has done this since the late 90s. And you can certainly configure it to index across shared drives.

Not suggesting it though :P