This tool has been released a while ago but many I heard are not aware of it.
In a scenario where you have to manage IT in larger organization you may find that departments are setting up an ad-hoc WSS deployments to facilitate your needs; mainly to avoid processes and routine.
SharePoint asset inventory – can scan a network range and display all of the statistical information about SharePoint deployments. Also, it leverages SQL Reporting Services to produce a report on how many documents, lists, items and other granular details are in your farm.
It also is great for audit and discovery process within your own network. One of the cool things I found is the ability to produce a network diagram based on discovered resources; the diagram is easily portable to Visio – very cool.
Check it out here.