Add into next version a cumulative total of space cleaned. Webroot's "Window Washer" has this feature & it is great to know just how much space is saved over time.
CCleaner appears to clean far more thoroughly than Window Washer.
This has been suggested before, and while I personally liked the idea, many felt that it was a little silly because certain things are just guarenteed to build up over time (browser caches, etc)
Devs do read the threads though, so maybe one day