There is an art book that I bought, which helped me with some of my lighting issues. It came with a disk that had scripts that are used in photoshop for lighting special effects. Lightning effects, torch light effects, star burst effects, they are all covered in this book.
The book is called Hi-Fi Color for comics, published by Impact. You can pick up this book at one of the larger book stores, Borders or Barnes and Nobles or 1 million books.

Unlike, NeonKnight, I really like photorealistic maps especially battle maps, it sets the mood of the adventure for me. However, NeonKnight is right about one thing photorealistic maps lack clarity.