Digital BW, The Print

>... I'll mention RealGrain from Imagenomic. It can be applied
> to 16 bit files, allows for layer use, can add grain, if you want to and
> gives you control over selective color channels. The down side is the pixel
> limitation that many plug ins can run into with PS.

For what it's worth, RealGrain is really excellent at simulating the look of film grain, right 
down to the differing image softness you would see from different film formats. It does an 
extaordinarily good job of disguising residual noise and interpolation artifacts.