BD links and resources
BD BioSciences is one of the biggest guns in the field of immunology, and their products and services span the entire globe. While their websites are no substitute for a good library or even a textbook, they are pretty informative. Here's a sample of their ELISPOT listings. (I found the cartoon depictions of ELISPOT assays to be particularly helpful.)
They also had ample other information regarding both the ELISPOT process and additional immunology information. These pages should provide a good starting point for self-education though. I found the cartoons to be particularly helpful.