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
Allowed Formats Jun 21st, 2016 This Drupal 8 module allows to restrict text formats on fields. Read more about Allowed Formats
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)
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
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
Media crop Jul 21st, 2013 (updated May 31st, 2016) Crop, rotate, resize images with CKEditor and the Media module. Read more about Media crop