Static Date Calls in Reports

It would be very helpful to have the option of adding static date calls in reports (e.g. Current Date, Last 30 Days, etc).  For instance, if I wanted to have see any students who had exited their program in the last 30 days, rather than having to change the month field each time I run the report, I could just add a static Current Date, and Last 30 Days to the Less than and Greater than ranges, respectively.