Gannet: Thanks for your feedback. We need a configuration application! :-) Or maybe, I'll just make the HTML templates more customizable, so that power users can easily change the columns that get displayed.

David: I am already experimenting with the file types story. File types and file extensions are defined in the Info.plist files inside application bundles. So, if you put BetterZip on your hard disk, the system will learn that cbz-files are actually zip files, because it is defined in BetterZip's Info.plist. What I am testing is, whether you can also define file types in QL generator bundles. Since Info.plist files are XML files, you could then add whatever extensions you want.