Six pack abs are possible, if you put in the time and work. This instructional video demonstrates simple exercises you can do to sculpt your abs. Rememeber, abs don't just happen over night, but stick to it. Llittle can compare with the satisfaction of looking down at your own washboard stomach.
When you do the bench crunch, your chest can go below parallel, so your abs get worked out over a greater range of motion than when you do a regular crunch on the floor. This makes the bench crunch a little bit harder, and a lot more effective at building your abs. The bench crunch is also better than regular crunches because it forces your abs to stay tight throughout the exercise, since you cannot relax your upper back on the floor. This is a mistake many beginners make, and it makes regular crunches way too easy, and not very effective at getting you six pack abs.