The EventDispatcher component provides tools that allow your application components to communicate with each other by dispatching events and listening to them.
The VarDumper component provides mechanisms for walking through any arbitrary PHP variable. It provides a better dump() function that you can use instead of var_dump().
The Config component helps you find, load, combine, autofill and validate configuration values of any kind, whatever their source may be (YAML, XML, INI files, or for instance a database).