This is based on Marshalmix's source code lister. I kept the sorter and display functions, they worked just fine, but I changed the rest.

1. Instead of having to modify the program to add exclusions, three lines per file, I changed it to use a database driven exclusion list and an admin page which supports adding/editing/deleting, enabling/disabling, sorting, access levels, etc.
2. You cannot enter duplicate file names. If a file name is already contained in an excluded pattern, it advises you and does not add it.
3. Any file (except for types like archives, media, and images) can be set to allow administrators to view.

There's a copy on SnitzBitz if you're interested.

I took another look at this mod and decided to improve it further. Now you can add/delete/edit sub-folders (from the same admin page) which are then automatically included by the source code lister. If you try to add or edit a sub-folder which does not exist, you'll receive an error message.