Hyperlink-icons-with-CSS is a project mainly written in ..., it's free.
A CSS module that adds icons after hyperlinks depending on hyperlink targets extension or URI-scheme.
This is a CSS "module" essentially consisting of an image (a sprite image) and a stylesheet for you to add nice little icons to the right of hyperlinks that lead to a file with a certain extension. Find examples in index.html. Source and sprite image are about 16kb uncompressed unminified.
Tested successfully in Firefox, Camino, Safari, Opera & Internet Explorer 7 (6 doesn't work)
For production, simply use the hyperlink_icons.css as a stylesheet and make sure that it is referencing the sprite.gif image correctly. This should make links look like the examples in index.html