solved:
* edit requires valid user (password is plain text by now)
* habtm (using simple form)

pending:
* has_many with ajax (add 1 or more ingredient while editing/creating the recipe)
* comments (this should be quite simple with simple_form)
* block new user creation or moderate it with admin user (id 0 or 1)

extras:
* inter user messages (140 chars)
* random recipe
* search by ingbredient
* search by tag/cartegory