Summing values based on a dynamic date range

I have two lists (see enclosed file) that will keep growiing as time goes on.

On the "Summary2" page i basically want to calculate something based on the a start and stop date.

in the example the start date is 6/1/11 and the stop date is 8/1/11.

I want to calculate something based on the start and stop dates for a list that i guess is dynamic in that it keeps growing with time.

Any ideas on how to do this without using vba macros.