Dumbbell Side External Rotator Raises - Lie on your side on a bench with the "up" elbow against your side so that your upper arm is parallel to the floor and the forearm hanging down in front of your body (dumbbell in hand, knuckles out).
With the addition of an adjustable ab bench or other simple weight bench, you can get a full workout for both your core and extremities by following the guidelines of either videos, books, or just a dumbbell exercise chart.
The Internet - Many sites will have downloadable and printable dumbbell workout charts that cater to all sorts of exercise demographics - from full-time stay-at-home parents to jetsetting business professionals.
If you don't mind working from your computer screen, you can keep your computer open while you work out, and actually follow dumbbell exercise charts with videos explaining the correct form for each exercise.
Strength training for weight loss is more than just picking up a dumbbell, but by choosing the proper exercises and doing them conscientiously, it is possible to reap the benefits of a stronger, lighter body.