Did you know that your washing machine [1] might not be washing the germs out of your family’s clothes? 
Over time, washing machines can become contaminated with bacteria, potentially leaving millions of germs behind in your laundry [2].
To correct this problem, run the washer without clothes using just hot water and one-half gallon of bleach. The bleach will sanitize the machine and all its plumbing components, killing any bacteria that have been left behind.
Remember, periodicially clean the very tools you use for cleaning -- it's worth your while!
Links:
[1] http://moneypit.com/audio-q-a/get-rid-washing-machine-odor
[2] http://moneypit.com/tip/cleaning-your-washer-and-dryer