These are my custom plugins I've written for Ansible (https://github.com/ansible/ansible):
This plugin mimicks the behavior of group_vars and host_vars in the inventory and playbook in the user's home directory (~/.ansible to be exact).
_host_allowed_facts
and _group_allowed_facts
can be empty (allow any facts) or contain a list, in which case it will filter out any other facts.
This plugin adds a jinja filter to your runtime (humansizetobytes) which converts Human readable sizes into bytes.