I use actinics that produce most of their light in the violet and low ultraviolet ranges. it probably actually stunts the plants growth, as most studies involving UV have indicated, but it also typically induces an increase in red pigments. I like to think of it as a plants version of a tan. most flourescent bulbs produce at least a little UV, but some produce mostly UV.
like I said though, i use them because they make the plants turn different colors. one strong UV source is enough for me to see that affect. I haven't tried my blue LED panels on very many plants yet, ill have to play around more with them to see if I can elicit a similar response in other plants.