Saturation equalizer is saturation plugin that can adjust saturation of an image via 6 sliders – effectively the saturation curve. You can alo modify brightness of image with two spinboxes – they work like „levels“ tool.
Additionally you can autoalign RGB channels to eliminate color cast and there are few more features. I believe they are self-explanatory, once you work with plugin.
It internally works in floats, that means no information is lost during processing.
Plugin is multithreaded.
To learn more visit homepage (with examples): http://code.google.com/p/satequalizer/wiki/Introduction