Common applications include the Facebook-style list builder for message recipients (F6) which provides a textarea with an auto-complete function and the ability to re-order and delete recipients. The Apple Mail style builder (F7) adds an action menu next for each item that can be used to offering multiple actions. This supports re-ordering via drag and drop, plus keyboard shortcuts to select and delete items.
This code is open source and can be found at https://github.com/michael-lang/jquery-ui-listbuilder.
Planning wiki: http://wiki.jqueryui.com/w/page/12137993/ListBuilder
1.0.1/1.0.2: rename delimeter option to delimiter to fix spelling. Old delimeter option name still works for now, but will be removed at a future date.