One of the projects I'm enjoying working on right now is the Eucalyptus Recipes project, which you can find on Github. I actually hacked together some code, and even checked it in! Needless to say, patches welcome. And if "patches" means "complete replacement with better code," that's fine also.
The goal is to build a collection of recipes (small right now, but growing) that any Eucalyptus user can inject into the boot process of an instance at start time, using cloud-init or a similar mechanism.