AqHome Control System GUI
This is a simple GUI which allows microcontrollers to use a display. It is completely written in AVR assembler and therefore rather small and fast.
It provides layout elements (horizontal, vertical, matrix) which allow for dynamic GUI elements. With those elements the widgets don't have to be individually placed by hand, rather placement is delegated to those layout elements.
This makes it very easy to change existing dialogs since the placement doesn't have to be recalculated manually.