Sharepoint usage statistics across all sites in collection?

Is there a way of getting usage statisics across my whole Sharepoint 2007 portal? I can get the figures at a site level by appending _layouts/SpUsageWeb.aspx to the path, i.e. http://intranet/teams/hr/_layouts/SpUsageWeb.aspx for the HR page or http://intranet/_layouts/SpUsageWeb.aspx f开发者_如何学Goor the front page.

What I'm trying to do is see how many unique users access the portal (across all the sites it contains). Using the above method on each site and summing the total users for each doesn't take into account users who visit more than one site.

I've seen commercial tools that seem to do this but surely there has to be built in functionality that does this for a product as all-singing-and-dancing as Sharepoint?

The URL of the site collection statistics page is http://intranet/_layouts/SpUsageSite.aspx.

This functionality does not exist in SharePoint 2007. It was added to SharePoint 2010. You can now report on stats in central admin for web applications etc.