Chyrp is a blogging engine designed to be very lightweight while retaining functionality. It has powerful theme and extension engines, so you can personalize it however you want. The code is well-documented, and it has a very strong structure that's loosely based on the MVC design pattern. Chyrp allows importation from several different blogging engines and uses a system called "feathers", which are basically templates for custom posts.
protective protects active records from being destroyed in a declarative way: < protect_if :attachments, "Record has attachments and cannot be destroyed" > . Of course, you may pass the name of any defined method. If its result evaluates to present?, the record is not going to be destroyed. No exception is thrown, but a message is added to the errors object of your model. This may then be used further on.
render_inheritable is a Rails 3 plugin that allows one to inherit or override single templates for controller hierarchies. With this gem, a template is searched in the current controller's view folder (as usual). If it is not found there, the template with the same name in the view folder of the superclass controller is used. Finally, views and partials remain DRY.