Django auth system: adding user to group via "invites"

I want to use the Django default auth system to manage users and groups. Is there an existing Django app/module that adds users to groups by invites? I.e. some existing user of the group sends an invite with a secret key in a URL, and another user that cl开发者_如何转开发icks on the URL joins the group.

I can write one, but figured I ask before doing that.

Thanks.

I am not sure if this will solve all your problems but do take a look at Pinax. They have features to support user invitation and user groups.