Definition: a method of physical and mental exercise involving stretches and breathing that focus on strengthening the abdominal core. Named after Joseph Pilates, designer of the system.
I am a big fan of pilates. They are the best exercises for your abdominal core. And they will help you to have beautiful posture (something I am trying to improve) which is important, not just for looks, but for keeping your whole body strong.
Here's the thing. Pilates are usually performed on a machine, with a personal trainer. This would seem to be the most effective way to get results, however, it is also the most expensive. I have always taken pilates mat classes. Which don't use machines, and are performed in a class of up to 20 people. They are a lot less expensive, and you still tend to get some personal attention from the instructor. The main thing about pilates, (actually about any exercise plan) is to be consistent with your workouts. If you are, you will see results. If you haven't ever tried them, give it a shot!
This post from FitSugar offers some great ideas on how to recession proof your commitment to pilates.