There is a page on that lists several controls that have been submitted as part of the OpenNTF Development Contest.

XPages Extension Library
80 additional out of the box controls.

XPages Mobile Controls
This project contains controls to assemble easily mobile apps for iPhone, Android and Blackberry. There are also samples showing access to native services and offline functionality.

XPages Demo Application
This application contains many different little samples showing the different functions from XPages live in action.

XPages Toolbox
The XPages Toolbox provides several features to monitor XPages applications. There is a CPU profiler (see screenshot), a backend profiler, run time monitoring, a memory inspector and logging functionality.

Plugins Deployment for Domino
This is an extension to the update site template to easily deploy plugins like the extension library to Domino servers via an NSF (note: this might be part of 8.5.3)

XPages API Inspector
This control shows the native Java APIs of XPages controls in the UI.

Social Enabler
Tools and controls to easily connect to social networks like Connections, Twitter, etc. via REST APIs and OAuth.

Login Control
Customizable login control.

XPages for Connections
Controls and samples for how to extend IBM Connections and how to access it via XPages.

XPages Business Card Controls
This project contains two XPage controls that can easily be used in custom applications to bring up the Lotus Connections business card.

Voting XPages Control
This project contains XPage custom controls that can easily be used in custom applications for simple votings. Technically it uses the DoJo dojox.charting.DataChart class.

Bookmarks for Lotus Connections
This control can be used in custom applications to display bookmarks from Connections from a specific user. Technically it shows how to use Dojo Atom utilities and the Domino proxy server to work around the one domain security restriction.

Control that makes usage of Dojo charting very easy in XPages.

XPages Name Picker
A picker control for selecting notes names out of the Domino Directory, inspired by the Facebook namepicker.

Tree XPages Control
This project contains a reusable XPage control to display data from a Notes view graphically in a Dojo based tree control.

XPages Control for Sametime Names
This XPage control can easily be used in custom applications to 'Sametime' enable person names. These names show then the online status and allow initiating a chat.

XPages Multi Attachment Custom Control
This XPages custom control is a multi-file upload control that uses a central attachment repository db for all the attachments.

XPages Dynamic View Control
This custom control receives a series of parameters and will dynamically build a view on page load.