The Site LivePipe is very famous for its presentation of some of its high quality widgets and controls for web 2.0 applications built using the Prototype JavaScript Framework. Each of its controls are well tested, highly extensible, fully documented and degrades gracefully for non JavaScript enabled browsers where possible. This site is actively maintained.

Event Oriented Programming:

It introduced a mechanism to create and observe events on any object, not just DOM Elements. This is used by all controls , and allows for fine grained control of your user interface.

As of now they have showcased so many controls like Tabs, Window, TextArea, SelectMultiple, Rating, ProgressBar, ScrollBar, ContextMenu. Just click and experience the world of good and efficient way of building widgets.

Just go through the Widgets which they have showcased perfectly and learn accordingly.

Recently they have showcased Window control which is awesome, this is Control.Window which is a fully programmable, multi purpose windowing toolkit for Prototype. It covers a wide variety of use cases and allows for a high degree of customization. It can attach to links to open the targets as windows, or can be filled with dynamic content. It includes support for stackable, draggable and resizable windows. Subclasses to handle Modal windows, LightBoxes and Tooltips are included.