Recently, I purchased/downloaded a plug in for Photoshop called Alien Skin Exposure 3. It is a very intuitive plug in that applies a filter that mimics what the photo would look like if taken using different types of color or black and white film/slide stock. It also has older film process types like Palopan and Daguerratype. Both the black and white and the color filters are amazing! I have been using the black and white ones on my most recent landscapes and the color ones on my most recent bird photos. What's nice is that it is not a heavy-handed filter. It adds qualities to the image without overdoing it.
Here's an example. This image is without the filter applied.
And here's it with. Notice how much richer the blacks and colors are, but it's not by any means over the top. In this example, I chose the filter that mimics Fuji's Provia 100 film.
One can get pretty crazy with this filter, but I like it for its accuracy in mirroring film and slide processes.