There are no magic pills that will make you lose weight without some work on your end as well. Most pills will work to some degree, but the effects are usually temporary because they simply flush the water out of your body.
Some people have claimed that green tea supplements help to speed up metabolism, as does vitamin D. There are some studies that suggest this to be true. Most diet pills mess with your hormones and add chemicals to your body that shouldn't be there. I would suggest really researching anything you plan to take.
Remember, a healthy diet and exercise can do more for you than any pill ever will.
Current Goal: Wear Size 10 Pants by September 1st