We've just released the Nimbus Theme for ExtJS 4. Check it out. We've done our best to give a completely different look and feel to the standard Ext JS theme (not just change $base-color ).
We'd love to know what the rest of you guys think of it!
Take a look at http://EdgeUX.com
Update - To celebrate our arrival on the Sencha Market the complete SCSS Source/CSS and Icons are available for £19.99
We hope you all enjoy it!