The Boston Globe recently had an article on NStar's little known "time of use" electricity billing option.  Basically, if you sign up for this voluntary program, you will pay less for electricity during "non peak" hours.  Summer peak hours are Mon - Fri from 9am-6pm.  Winter peak hours are Mon-Fri from 8am-9pm.  All other hours are "non peak," including holidays and weekends all day! I found out that you do need to commit for a year, but if you already do all your laundry at night, you could save some money!