You can generate access token for your Pinterest account for existing apps that have been approved by Pinterest such as the Pinterest for iPhone:
https://www.pinterest.com/oauth/?consumer_id=1431594&response_type=token
That are public and do not require access_token:
https://api.pinterest.com/v3/pidgets/boards/[username]/[board_name]/pins/
https://api.pinterest.com/v3/pidgets/users/[username]/pins/
http://api.pinterest.com/v3/pidgets/pins/info/?pin_ids=521150988102375972,10133167885969245
http://api.pinterest.com/v1/urls/count.json?url=[urlEncodedLink]
http://pinterestapi.co.uk/jwmoz/pins
http://pinterestapi.co.uk/jwmoz/boards