Stuart Robertson has released his Comic Gallery Script to the public under a Creative Commons/GPL license. I’m not 100% positive, but I believe the PV Comics site runs on a version of this script.
* Start with the first or last image in the directory
* Display navigation above or below images
* Back and Next links
* Back and Next arrows
* Direct links to each image
* Configurable number of links per line
* Customizable dividers between links
* Display the copyright owner
* Display a link to your Creative Commons License
There’s also a forum thread discussing a number of scripts at Blank Label Comics.