simple clean twitter button ui design 500x254 - Blue Twitter Button

This shows buttons that are bright and bold can stand out on a dark background. Designer: Ryan Johnson Source: Dribbble

Blue Twitter Button

power button ui design free psd 500x254 - Power Button

This power button shows how lighting and can be used to give the button a 3D look that beckons to be pushed. Designer: Pontus Johansson Source: Dribbble

Power Button

play button loader user interface design element 500x254 - Play Button

This is a great example of dark ui elements done correctly. Designer: Lukas Majzlan Source: Dribbble

Play Button

dfsfgsdfg1 - Map UI

  This combination of Google maps and clean icons provide an excellent user experience.

Map UI

weather app big21 500x584 - Weather App

  A very clean design with a great minimal colour palette.  

Weather App

web elements psd 1 by lewisbell d3cfp5g 500x286 - Web Elements

Source: http://lewisbell.deviantart.com/art/Web-Elements-PSD-1-202286356

Web Elements