I workout 4 times a week, mainly power and weight exercises. I have a thin athletic build, but can't get rid of 2-3 pounds of fat around the abdomen that hide the 6 pack. What is the best exercise to get rid of that annoying fat?
Same way you burn any other fat; expend more calories than you consume and increase your muscle mass--there's no such thing as spot reduction. (I also tend to avoid carbs after dinner, but it's not clear to me that doing so makes any significant difference.)
Diet is the biggest factor--don't underestimate the amount of dietary discipline in that cover shot.
You can't spot reduce, but you'll lose weight as long as you burn more calories than you consume. So eat less and exercise more, and weight loss is guaranteed.
Also, you say you mainly do power and weight exercises. Try more cardio, such as running, which burns far more calories per hour than strength training does. (As far as I understand, the notion of "after burn" with strength training is a myth. Also, just intuitively, look at avid runners as a group you'll be hard pressed to find another group of people with body fat percentages as low as theirs.)