Formula to display the last day of the previous month

I am using the following formula to show the first day of previous 6 month cycle.

=DATE(YEAR(TODAY()),MONTH(TODAY())-6,1)

That formula would display: 07/01/2009

I want to have another formula show the last day of the previous month.

Basically it would display: 12/31/2009

I appreciate any help with this.

thanks,
Nick