There is a new diet out there called the OMG get skinnier than all your friends.  Basically you have to really have to discipline yourself for 3 weeks, but you will burn lots of fat doing it.  Here is how it works.  Wake up, drink black coffee, exercise, sit in ice water, eat three hours later.  This is supposed to encourage your body to burn calories from fat rather than calories from food.

Now if you want to target your abdomen then do these for the exercise part.