I tried NoiseNinja, but I wasn't overly impressed with it. Even though it can't do *everything* that Photoshop CS can do, I use Paint Shop Pro 9.01 to do most of my post-processing work. Most of my post processing work is just image sharpening, and the occasional removal of a blemish, so I can't justify spending almost $800 for Photoshop CS. The latest version of PSP has a digital camera noise removal tool written into the software, and at least to my eyes it does a better job than NoiseNinja.
I have some photos from my very first photo shoot that I took two years ago with my old Sony F717 that I thought were a lost cause. Between .jpg noise, and the exposure being off because of the glare of the ocean being behind the model, almost all the flesh tones and shadow areas had a LOT of noise. PSP's noise removal tool was able to clean up the noise pretty well. You can download a time-limited version of PSP 9 from www.jasc.com.