Since the start of the Low Impact Week excitement, if I may call it that, there have been several suggestions for adding hand washing your dishes instead of using your dishwasher as one of the low impact action items. I have always been under the impression that hand washing your dishes wasted a lot more water and that the dishwasher was way more efficient at cleaning.
So, I did a little poking around to make sure I wasn't misguided and found some information here. According to a study done at the University of Bonn, they found that a dishwasher uses one-half the energy and one-sixth the water as washing by hand. Oh yeah, and less soap too. Even the most conservative hand washers couldn't beat these stats, not to mention that the dishwasher-washed dishes came out cleaner to boot. Just make sure you only run full loads to maximize your energy and water efficiency.
Along the same line, I was recently inspired to start using the air-dry setting instead of running the dishwasher on heat-dry. It's not much extra work unless you have a lot of plastic containers, but they don't get all that dry with the heat-dry option anyway. I highly recommend it!