Module that allows visitors to suggest modifications on a node I'm looking for a module (or some other way) that allows users to send suggestions about how to edit a certain node. I'll explain:

There is a node type with the following fields: name, description and phone number. One node contains these values:
Name: "Lulu's Restaurant"
Description: "A very good restrurant"
Phone number: "123456790"

A visitor notices that some values are incorrect, clicks on a link "send suggestion" and he's brought to a form where the fields are filled with the node's data. The visitor edits the fields

Body: "A very good restaurant"
Phone number: "1234567890"

And clicks on "send", this will memorize the data on drupal (on a different place than the node, but this has to be linked with the node) and notifiy registered users of this new suggestion.
Registered users should be able to see a comparison view of the original node and the suggestion (possibly with highlighted text, like your typical diff checker application) and then edit the node accordingly.

Registered users should also be able to change the status of the suggestions (pending, accepted, not accepted, spam).
Another feature i need is that visitors (unregistered) should be able to subscribe to nodes and receive notifications whenever the node is edited.

I think some basic features can be done with normal drupal features (like a node that can be created by unregistered users) or the rules module for notifications, but i was wondering if there's a specialized module to do this.
Apart from the notifications, Workbench along with Workbench Moderation seems to meet most requirements.

Drupal only has two states for nodes: unpublished and published. With Workbench Moderation, you can define your own custom states, e.g. pending, accepted, not accepted, spam.
You can then authorize anonymous users to edit nodes (make suggestions). These edits will create new revisions which will NOT be published until authorized users actually publish the changes.

Workbench Moderation also works well with Diff which allows you to compare different revisions to see the actual changes per field.

Finally, following nodes and notifications can be realized with the Flag and the Rules module.