GUI (Graphical User Interface) Widgets are used everywhere in modern software. They make it easier to select and enter information.
They include: sliders, dials, combo-boxes, radio-buttons, toolbars, toggle-buttons...
See Widgetfarmer's forum post to see these organized by category! http://scratch.mit.edu/forums/viewtopic.php?id=5397
See wikipedia for more information:
This gallery is to showcase Widgets created in scratch.