@autopilot,
There is one thing that was not mentioned yet (i think): The skin takes more time to adapt. Once you lost a signifficant amount of weight and/or bodyfat your skin will obviously be still stretched from the bigger area it had to cover before. Most studies have shown it can take up to 1 year (depending on the tissue also up to 2 years) until the skin has fully shrunken and tighten up to your "new" shape.
If your tissue is very weak, or you went from a real oversize to being normal again (meaning really having had a 'lot' skin) a surgery might be in order because the skin can only shrink back so and so much. Especially also because being really oversized causes rips and tears in the skin tissue and it just is very destroyed in it's elasticity.
But no worries, the latter is obviously not the case with you.
If you keep loosing weight or bodyfat you might experience more loose skin for a little longer, until your body has adjusted.
A good diet, exercises, and some cardio will help.
Exercises for the lower abs, don't shrink the skin, but they make the area tighter and the muscle bigger, so it will fill out a bit of that 'empty' skin area.
Cadio will help to shrink what is often considered or thought to be loose skin, and is in fact still just a tiny fat layer on this stubborn spot, that many have to fight with :)
On top of that, even if prolly not considered a very 'manly' solution, you can help to speed up things a lot by massaging that skin area, and making sure to put some good lotion on it. The higher blood flow due to the massaging helps the tissue to tighten up, and the lotion will make sure it's getting its elasticity back.