Free PSD UI Kits
Impressionist UI Free – User Interface Pack
Futurico – Free User Interface Elements Pack
Free PSD/HTML Web UI Elements Kit
UI Kit
Blaubarry Ui Kit
Dark web and Apps UI Kit
Dark UI Kit
Light UI Kit
Moonify UI
Minimalist Dark Psd Web UI Set
Classic Grey Psd Web UI Set
Simple UI Elements
Cloudy Ui kit
Butterscotch UI Kit
Sleek UI Elements
Source: http://designmodo.com/free-psd-ui-kits/#ixzz1rNPq4VGE