Working with categories is a great thing. Currently categories can be assigned to different kind of records (e.g. content, news) where those records might be spread over various pages. Sometimes it would be handy to view all records (spread over various pages) for certain category selections in one panel. For this a module for category browsing/editing could be created.
Similar to showing a tree of pages with the page or list module the category module would show categories in a tree form. Clicking a branch would show a list from all records belonging to that category in the list panel. More branches should be selectable by pressing the ctrl-key.
The list panel could be as it is from the list module.