You may not have even noticed it, but at the very bottom of your Act! screen there's an an information bar, an area that displays a count of the items in the tab you have selected.
On the Notes Tab it displays the number of notes for that record, on the History Tab it displays the total number of history items. On the Activities Tab is shows not just the total number of Activities but also the number of Calls, Meetings, ToDos and Custom Avivities.
I would like to see the same functionality for the Documents Tab. Show the total number of attached documents, then the number of Word, Excel, PDF and Others.