"Hooks" Concept

How rad would it be to have a hooks concept? I would like to maybe think about it in the next couple days to see if I could help add this functionality.

What 'design' would fit best into the nsot world? Something that allows you to set up hooks to get notified about each resource modification, creation, and deletion. Really as long as the resource object can be passed, each hook could take it from there at the basic level. At a more specific level it could be worked so you create a network-hook or a site-hook, but not sure if there'd be much extra value there.

Thoughts?