Does the white stuff left on orange slices are you peel them have any nutritional value?!

While the orange's juicy part contains most of its Vitamin C, the white part is full of flavonoids. Your body utilizes Vitamin C better when it interacts with flavonoids, so the health benefits are great.

The white part is one reason that whole oranges are healthier than juice (because most orange juice lacks the flavonoids found in the white part of oranges.) This is true of Vitamin C supplements as well; the better brands (like Ester-C, my favorite) contain citrus flavonoids or rose hips (a source of flavonoids) in addition to the ascorbic acid (Vitamin C).

Yes, it has lots of nutitional value, as does the peel if you buy from organic where they don't shoot orange dye/paint into the oranges to make them look "good" as well as the pesticide spray, etc.
Some people say the whites help your teeth get white, but I have not found that to be effective.

Florida orange farms.

That's the pith, or otherwise, the pulp you see in orange juice. And yes, it has nutritional value.

Love oranges and orange juice with pulp!

well actually it has more vit C than the orange itself. The rind and the white (pith) are full of vitamin C.