The category filters in 4.5 used to give you a count of the amount of items matching that category.
I can't seem to find this anymore?
Similarly on the content type links, I'm sure there used to be a count so you could see how may items of each type of content there are.
Ok, so the content types do show you the count, but only if you make the page wide enough.
You could just do "icon (23)"
"icon documents (23)"