Most of the Impact sights have a significant amount of fiber optic cable used in the sight...2 or 3 feet if I remember correctly.

If you are into lights for sights then there are a variety out there that can be used as an " add-on" to any sight as well as ones that are specifically made for certain sight models.

...and as you mentioned there are also some radioactive pins available for a variety of sights. However, my experience with them leads me to believe that they are a bit too dull to work in the manner that they were intended. Ofcourse, I have only really played around with one of them so I cannot speak for all of this particular style.