I found out on cs5 there is a histogram equalizer with in hdr toning...I also found out that there are plugins for histogram qualizers. I did download one called kamflex it was ok but it was noisy. From my learned friends on this site can you recommend others and if so where is the best place to get them. Pornada (free)
Usually for most image editing you really shouldn't need that type of plugin. (it's similar to Image>Adjustments>Equalize)
Is there a specific problem your trying to solve?