If you use a wort chiller, instead of flushing all of the "waste" water down the drain, use it to fill up your laundry machine or at least use the water to begin cleaning up your equipment.

Leftover grains not only can be used to beef up bread recipes by adding interesting character and texture (though the starch/sugar benefits are gone) but also can be composted or used as a treat for farm animals.  When I lived in Utah, my apartment complex happened to be next to a plot of land with two long-horn cows who were some of my biggest brewing supporters.