This will create a simple list of links to files based on the contents of a google folder. You want to deploy this as a webApp with "run as me" and anyone even anonymous permissions. I have also found that this only works from an app account.
Modified for sites:
Site gadgets are not able to pickup the parameters so they needed to be built in, when creating a gadget script attatched to a site.
There is a restriction in Google Apps preventing it from being used in an iFrame, preventing the above solutions from being used in other CMS tools like Wordpress. To make this work I created a Document app that imported the file list. This allows for more customization in the look of the list. To get started open up the below document and click File => Make a copy. There are limitations, such as not being able to open the links outside the published iFrame. I suggest your going to file =Publish to Web on your new document and using the embed code in your Wordpress or other.