Heres something Ive been working on recently. Its a large patch of film grain.
From what Ive seen, Photoshop provides filters for all kinds of film grain and noise, but its all digital-camera style film grain, i.e. aberrant pixels of odd colors. I wanted actual film film grain, so I found a picture Id taken on very grainy film and extrapolated out the grain until it was large and even enough to use. I then adjusted the brightness so that, on average, it was about a 50% gray such that you could overlay it onto a picture in Photoshop without affecting the brightness of the original image.
To use this, merely hit download and save the image. Open it in Photoshop and copy and paste it onto an image in a new layer and then set the blending option to overlay. If this image is too small, you can copy and paste until the whole image is covered. If you want the grain to be larger, simply scale up this image. I hope its helpful for retro-fying your photos.
As with all of my resources, You need feel no obligation to link, note, credit or otherwise inform me of your usage. It is 100% free, even if you intend to sell the final product. That being said, it would inflate my ego greatly if you did let me know so I could see what you did with it.