I can only find one for mailboxes.
After some trial and error, I have found the privilege that allows a user to create a custom mailing list. They need to have the “Manage troop members” privilege turned on. This privilege also allows the user who has it to add, edit, or delete troop members. So, depending on who is needing to create new custom mailing lists, this may or may not be more control than you would like them to have.
It would be nice if this could be put into the User Guide somewhere.