Ok, this is a little weird, but here's the situation:

Column A has the Day of the Week: Monday, Tuesday, etc.
Column B has the numeric Date: 6/10/2008, 6/11/2008, etc.
Column C has the numeric Time: 6:00-6:30AM, 6:30AM-7:00AM, etc.
Column D has the numbers I need to average.

What I need to do is average all the cells in column D (D2 thru D500) based
on the day and time.

For instance:
Monday 6:00-6:30AM: #
Monday 6:30-7:00AM: #
Monday 7:00-7:30AM: #

I tried subtotal and I tried an Average(IF( array formula, but I can't seem
to get anything right. Here's the formula I tried:

{=AVERAGE((IF(A2:A500="Monday",F2:F500,"")))} - gets #DIV/0