You could try by using jQuery UI Resizable. It enable any DOM element to be resizable by dragging the cursor grab at the right or bottom border to the desired width or height.
I've put up a simple jsFiddle
demo for you here: http://jsfiddle.net/hmJCQ/
Update — as per OP's question in comment, for using jQuery UI Resizable
with jQuery UI Draggable
Updated jsFiddle
demo: http://jsfiddle.net/hmJCQ/1/