Wysiwyg Feb 23rd, 2013 (updated Oct 11th, 2017) The WYSIWYG module is my favorite for rich text editing in Drupal 6 and Drupal 7. (In Drupal 8, WYSIWYG is in core.) Here's how I set it up. Read more about Wysiwyg
Using hook_field_extra_fields to add extra fields to the display of an entity. Aug 4th, 2014 (updated Dec 15th, 2016) Not a lot of time to document this, tight schedule today, but I wanted to make sure this code didn't slip through the cracks. Read more about Using hook_field_extra_fields to add extra fields to the display of an entity.
Link class Jul 1st, 2016 For Drupal 8, adds the ability to add CSS classes to link fields. Read more about Link class
Display Suite Feb 23rd, 2013 (updated Jun 23rd, 2016) Provides some advanced layout and display options for content. "Display Suite is a module that takes over the rendering of entities." Read more about Display Suite
View Mode Selector Jun 23rd, 2016 This module adds a view mode selector field to any entity Read more about View Mode Selector
Field API Pane Editor (FAPE) Sep 12th, 2014 (updated Jun 7th, 2016) Allows for quick editing of field type panel panes. Read more about Field API Pane Editor (FAPE)
Focal Point Nov 25th, 2015 (updated May 31st, 2016) Sponsored by NBCUniversal, the focal point module seems to have been inspired by the image field focus module Read more about Focal Point
ImageField Focus Oct 25th, 2014 (updated May 31st, 2016) Lets you do cropping of images. Works with the picture module. Read more about ImageField Focus
Region View Modes Nov 5th, 2014 (updated May 31st, 2016) "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." Read more about Region View Modes
Paragraphs Previewer May 16th, 2016 (updated May 31st, 2016) When editing a paragraph, the Paragraphs Previewer module lets you see what it will look like before saving. Read more about Paragraphs Previewer