A plugin for Redactor.js (http://imperavi.com/redactor/) allows resizing of the editors areas (by drag & drop) either horizontally, vertically or both.

The implementation is straightforward:

1. Include resize.js (or resize.min.js) in your project
2. Add "resize" in "plugins" array while initializing redactor
3. Use either "resizeX: true", "resizeY: true" or both to enable drag-and-drop resizing.