New Feature: Triggers on Add/Remove Tag
You can now add triggers on adding or removing tags.
Tags can be a convenient way to organize your actions. Add a tag to a contact, and that tag then triggers an Automation to start, or some other set of actions to happen.
You can also include tags in your raw HTML opt-in forms: Add a field with the name "customer[tag_names]", and whatever gets passed in there will be interpreted as a comma-separated list of tags to add to the contact.
That way you can do a bunch of advanced conditional stuff with a little coding.