Replace the default “Set featured image” metabox with Drag & Drop Featured Image option for making faster uploads.
Drag & Drop Featured Image is a plugin that saves your time by giving you a shortcut for setting up a featured image. All it does is it replaces the default “Set featured image” metabox with a new one containing a Plupload drop area. It supports JPG (JPEG), PNG, GIF and BMP image formats.
Install and activate the plugin, configure the plugin through the Appearance => Drag to Feature options panel.