Oh my. I keep reading this thread on tummy help, and I keep reading on sit ups and crunches. Those only help show abs if you already are slim in the tummy area. The best solution I found for losing stomach fat is actually more of a post workout thing. Spend workout routines doing average weight training, then end it with about a 10-15 minute intense cardio routine. Not only does this burn a lot of fat during, but also burns post workout. Eating healthy is also a good part of this. Which reminds me, after working out, it's good to not eat for about 30-45 minutes to make sure your body gets its maximum amount of fat burned for that workout session.
That's what I do at least and it only takes about an hour out of my day. More if I go to the gym after work as well.
If you're already slim in the stomach area, yes sit ups, crunches, flutter kicks, and planks will most definitely help show ones abs.