Since many others are asking for this plugin, i'm posting the plugin and adapter for highcharts here.
For people who don't know Highcharts:
[Last update 09-11-2010: Highcharts 2+ required!]
* Version 2.+
* Fixed the refresh bug. (Do not render if chart is not ready yet)
* + Added class: Ext.ux.HighChart.Serie, Ext.ux.HighChart.LineSerie, Ext.ux.HighChart.PieSerie, etc..
* - Fixed: Wait for the panel to be resized to its correct size (Instead of 0,0) after that create the chart.
* - Fixed: Series keep hidden after resize.
* + bindComponent - Fixes the issue with the fitlayout.
* + setTitle, setSubTitle - Change the title/subtitle of the chart
* + addSeries - Add new series to the chart