I used Disk Inventory X for years to do exactly what this application does. I figured it would only be a matter of time before DIX broke with the latest OS, since it appears to be no longer in development. To DIX's credit it has worked flawlessly with every system from Jaguar to Leopard. GrandPerspective appears to be a worthy successor, with a few more useful features and a chance that user feedback and requests may actually make into the application.

Nice work!