Get Daily Average Sales for a range of dates

I'm trying to analyze my data to see which days of the week are the most profitable on average....

Simple Example
Column A is the date (ie. 9/27/2010)
Column B is the amount Profit/Loss (ie. $200)

I want to use the date range (A1:A150) to calculate the average P/L for each specific weekday but can't seem to figure out how to make it work. Anyone that can provide any quidance is greatly appreciated.

Trying for results like this
Monday: "Average Monday Profit Loss"
Tuesday: "Average Tuesday Profit Loss"
Wednesday: "Average Wednesday Profit Loss"
etc....

An actual sample set of data is attached.