Sum'ing groups of data

Hey All,
I have a list of dates with data next to it. I need to figure out a way to get the sum of every 7 dates as a line item.
For example: I need it from Tuesday to Tuesday and then a line item with the total next to it.

Tuesday, February 17, 2009
Wednesday, February 18, 2009
Thursday, February 19, 2009
Friday, February 20, 2009
Saturday, February 21, 2009
Sunday, February 22, 2009
Monday, February 23, 2009
Tuesday, February 24, 2009
Wednesday, February 25, 2009
Thursday, February 26, 2009

Anyone have a thought on this?