"Panels are great, but how do I change this one page?"

"Some content/nodes should never be viewed directly; only visible be through something else such as Views or Panels. This module denies access to node/[nid] URLs while allowing the content to stay published and otherwise viewable."

Also see Rabbit Hole

"A system for building "megamenu" -style (explanation) dropdown menus using Mini Panels, which provides tremendous flexibility in what can be displayed." Read documentation from Damien McKenna: https://drupal.org/node/1358006

Otherwise known as ECK, Entity Construction Kit allows the creation and management of new fieldable entities in a UI.

Entertaining presentation on usage from DrupalCamp London 2014: http://youtu.be/hhUuv1cEgVY

https

Make all external links open in a new window. There are optional custom exclude/include filters.

Lets you use tokens to embed video and have the ability to add a button to the WYSIWYG for easily adding a video (for those to0 lazy to type).

Flag is the ultimate bookmark tool. A must learn module.

The de facto date field for Drupal.