Once you get past the regular AdminCP Options and Style Properties, you might feel inclined to start doing some custom development against XenForo. One of the most useful ways of doing this is by having your code listen to events that are fired by the XenForo classes. To enable you to do this, XenForo exposes a number of events, to which you can listen by means of Code Event Listeners. In order to provide you with a quick oversight of the available Code Events, see the attached document. It is currently up to date for XenForo RC2, and will be (attempted to be) kept up-to-date with future releases. I added some minor notes on the MVC definition of "Model", "View", and "Controller", but perhaps Mike or Kier will be kind enough to add a few additional comments on some of the other classes that expose events, and their intended use.