使应用程序可定制的最佳实践？

I'm interested in reading about the various ways other developers and architects deal with the customization of certain areas of their applications for certain sites. Call outs to customer implemented pre and post processing, events doing the same, allowing business logic methods to be overridden, using strategies with pluggable modules, data configurable processes, e.g. rule engines, scripting, etc. I'm interested in reading about the various way