@Sam Blows - your solution is great but will not work on IE9. The chart catches the mouse events and prevents the click on the jQueryUI resize handlers to start a drag. You could solve this by setting the background color of the handlers to some color (not transparent) and setting the opacity to 0.

Found this today, might be useful for those reading this.

http://jsfiddle.net/blowsie/xcsX9/

egret230: not bad. I am waiting for a new release of highcharts if that takes to long i might go with your fix until the next release.

I'm kind of already doing this using JQUERY UI:
http://jqueryui.com/demos/resizable/

Before creating the chart, I first destroy() the resizable that I had previously added.

Then, after creating the chart, I add it back in:

$("#actual_chart").resizable({
minWidth: 500,
minHeight: 350,
containment: '#chart_container',
stop: function(event, ui) { BuildChart(); }
});

When someone resizes the chart, I call the BuildChart() function to re-draw the chart in the now resized dive.

It works pretty good!

+1!