This site attempts to allow a comparison of the grain given by different combinations of film and developer.
The images you see are 1:1 crops from 4000dpi scans of negatives. There are a few images of each film trying to focus on different lightness, contrast or effects.
Each film comes with notes on the film type and the development process used. Tables listing the films by type, developer and pushing can be found at the right.
I also started a flickr group on this topic. Please join if you have similar images to share.