Simple Flat UI Kit. You can basically build fast mockup interfaces without any hassle.
The UI Kit will grow in the future.
Changelog v1.2:

Redefined buttons

added button group
changed dropdown buttons
added different button sizes
added button states

changed module width to fit in 960 grid
changed message style
added login module

Changelog v1.1:

Uses free font “Oxygen” for text
Resized basic elements
Added article boxes
Added calendar
Added mail box
Added pagination
Adjusted style of todo list & settings box

Features:

Full layered and editable
Uses FontAwesome for icons
2 Button Sizes in 3 different button colors
Dropdown Button
Button with Icon
2 Checkslider styles
2 Checkbox styles
2 Radiobutton styles
Notification messages