The ability to move an item from one list to another.

Having various lists is valuable. Sometimes, however, you need to move an item from one list to another. For example, you have a list of books you want to get at the library, another for books you want to buy. You get a book from the library and realize you want your own copy. While you can delete it from your Library list and retype it in your Bookstore list, it would be simpler to just move it from one to the other. Perhaps a "move to" function under the Edit menu.