You can go to the Notes Report to answer questions like How many Phone Calls has Kevin Smith made this week or last month. The Notes report has both simple and advanced filters to give you the power you need to drill down into your users's activity.
This report can also be used to answer questions like How many Phone Call's did my sales agent Kevin Smith make last month, how does this compare to other users?
The bottom of the report will total the number of Notes filtered on.
By defining Note Categories when you get set up you can easily filter on the attributes and even export your selections.