Right now you can only report on record counts and numbers for graphs and matrixes. You can do a CNT (Count) and DCNT (distinct count) on strings but these don't appear in graphs or the summary.
Please allow users to Count strings and include this in a report. A common use case is to see the numbers of projects that a particular worker has worked on in the past month whether or not they are complete. You could do this in an hour report but you'd need to use dcnt to get the proper number of projects.