Well, not exactly standing... more exactly the opposite (but it's not sitting or lying, so maybe it'll fit the bill for you). My favorite ab exercise (may or may not have a name):
Get up on the pullup bar. Actually the two parallel handles work better, but anything you can hang from works. Keeping your legs straight and your torso more or less perpendicular to the ground, lift your legs above your hands. Don't swing as this will render the exercise useless.
This can be hard the first time you try it. If needed, bend the knees a little.
It's basically like a v-up, but you go from completely straight to very bent, and get a lot more resistance from gravity.