ability to select uris rather than just local files. you must use a gtkfilesystem implementation that supports this, for example the gnome-vfs backend.

present a list of application-specific shortcut folders. for example, a paint program may want to add a shortcut for its /usr/share/paint_program/clipart folder.

define custom filters so that not all the files in a folder are listed. for example, you could filter out backup files, or show only image files.