"Every now and then a new product comes along that redefines expectations. In software-based noise reduction such a product is Noise Ninja from Picturecode. Last year it was Photokit Sharpener Pro, which revolutionized image sharpening, and now it's the whimsically named Noise Ninja."
Noise Ninja is available in two version. Picturecode has a Home Licence which is available for $29, which takes care of 8 bit files, but it does not allow batch processing. For those of you looking for a fuller featured product, there is the Professional License for $69 that can take up to 16 bit files and features full batch processing. If you can afford the price, then it seems like the Professional version would be the one to get. Noise Ninja is currently only available for Windows, a Mac version is supposedly going to be available in Q2 this year.
I haven't used these personally, but I can see how these would be very useful.