First, be sure to thoroughly clean out your detergent container.
1. Hand washing station. For the spigot-style containers, use in your garden, bring along on camping trips or keep in the back of your car to wash off dirty hands.
2. Store stuff. With either a regular detergent container or a large spigot-style container, cut off the top or one end and use the remaining piece to store things in your laundry room (clothes pins) or garage (rags, nails, etc.). Instructables has an awesome photo tutorial for an entire organizing system using laundry detergent bottles.
3. Funnel in the garage. Cut off the bottom of a jug of detergent and use the top as a funnel for changing oil in your car.
4. Sharps container. Safe and practical disposal of insulin needles.
5. Measuring cup. The lid holds approximately 1/2 cup.
6. Watering can. Wash the container out very well (removing all soap residue) and use as a watering can for indoor and outdoor plants.
7. Scoop. The handled jugs work perfectly as a scoop for grain, seed, dog food, etc. Wash out very well and cut off the bottom of the jug and use the top handled portion as your scoop.
9. Weights. Fill with sand, weigh on your bathroom scales and get lifting!
10. Salt sprinkler. Fill with deicing salt and use in the winter on sidewalks and driveways during icy weather.
Bonus idea: Refill an old detergent container with homemade detergent! Check out The Simple Dollar for a recipe and tips.