Ron Pacheco has a tutorial on how to reduce noise found in some digital images. The process is not for every image nor everyone because you can spend a lot of time and get a very small bit of improvement. In addition, if you overdo the corrections you can end up with an image that looks worse than what you started with. But, like any tool, if used right it can make a difference.
I'm running late this morning so I gotta go.
Aloha!
