"A surprisingly simple, flexible layout solution made possible by placing fields in regions. Region View Modes is just a bit of glue to join Drupal's theme regions and View Modes."

The Replicate Paragraphs module makes it possible to copy Paragraphs to make new ones.

"Defines a field type Block reference which allows the block to be displayed as the content of the field." Alternately, if the bean module is enabled, blocks can be referenced using the entity reference module instead.

"Fieldgroup will, as the name implies, group fields together. All fieldable entities will have the possibility to add groups to wrap their fields together. Fieldgroup comes with default HTML wrappers like vertical tabs, horizontal tabs, accordions, fieldsets or div wrappers."

Rabbit Hole is a module that adds the ability to control what should happen when an entity is being viewed at its own page.

Also see Internal Nodes

Used on http://drupal.org, "This module stores the changes of a node into a field attached to comments allowing to display a kind-of activity stream on the node much like on drupal.org issues just with a lot less custom code."

There is a great article that shows how all of the Acquia sites are architected. In that article, it is mentioned that Services is used quite a bit to power REST endpoints. Here is a really, really, useful tidbit that I don't want to forget which comes from that article.