Move or remove posts in bulk by category or by tag.
Bulk Move is a WordPress Plugin which can be used to move posts in bulk from one category or tag to another. This Plugin can also be used to remove posts from a certain category or tag.
If you looking for deleting posts, instead of just moving them, then use Bulk Delete Plugin instead.
If you are not familiar with either git or Github then refer to this guide to see how fork and send pull request.
If you are looking for ideas, then you can start with one of the following TODO items :)