Do you really need a plug-in?
Version 10 adds a new professional style, three-level Color Corrector (as well as a Color Enhancer) that is almost as powerful as the one in Premiere Pro!
A true white balance correction plug-in is no comparison to using the three-level Color Corrector or Color Enhancer.
If anyone has done extensive work on still images in Adobe Photoshop as I have, there's absolutely no comparison.
Yes, one can noodle around with the existing tools and kind of get there, but it requires a strong working knowledge of color balance variables.
A white balance plug-in has a simple warmer / cooler slider and can adjust white balance in a couple of seconds without skewing basic color components.
Another color corrector plug-in I know about is "Color Fixer Pro" in the NewBlueFX Video Essentials V collection. You pick a color with the eyedropper, then make adjustments with the correction slider. That's basically it, but there are other sliders. That collection is $99.00 US. http://www.newbluefx.com
Good suggestion. I have not used the NewBlue FX Video Essentials, but took a look at that one, and it does seem to be just what the OP is looking for.
I like the Fast Color Corrector (in PrPro), and the Three-Way Color Corrector (now with a slightly modified version in PrE), and they work perfectly for me. They are not a "one-button" Effect, but their power is amazing.