This XPages library offers demonstrations of...
Custom ApplicationFactory
Custom FacesContextFactory (including custom ExternalContext)
Custom Lifecycle
Custom Component & Renderer (HTML5 Canvas)
Custom Expression Language Bindings
PhaseListeners
ApplicationListeners
SessionListeners
FacesContextListeners
ValueChangeListeners
ActionListeners
Custom PropertyResolver
Custom VariableResolver
Custom ViewHandler
NavigationHandlers
Custom StateManager
Resources and ResourceProviders
SSJS Library Provider
ManagedBeans for all 4 scopes (Application, Session, View, Request)
SessionScope generic storage map (be cautious with this, as it's
a bad idea to share content that should be secure)
Implicit globals for SSJS