Suppose you're having a birthday party, and you're making your friends register for it. (You're weird.)
You create a Registration card with a bunch of structure to determine the fields they have to complete. Then, when they submit the registration, you want to receive an email to notify that they've registered.
First you create an Email template called "My Birthday Email" and set it to be delivered to you.
This means that whenever a Registration card is successfully created, you'll be emailed!
Action extension rules work like any other Wagn rules:
In this case, the interface for, say, an *on update rule is basically a standard Pointer interface, which means you're basically editing a list of cards. In this case, the list of cards is a behavior to be taken with the given event.
In the near future we expect to see mods for supporting many other kinds of behaviors, including things like "tweets", "requests", and other integrations with other software.