Smart Trim implements a new field formatter for textfields (text, text_long, and text_with_summary, if you want to get technical) that improves upon the "Summary or Trimmed" formatter built into Drupal 7

From the project page: "Simplify allows particular fields to be hidden from the user interface. This helps to de-clutter forms and present a more user-friendly experience to content editors..."

The htmLawed module enables the use of the htmLawed(X)HTML filter/purifier with text/input formats.

This module lets you use very fine grained html filtering.

See /docs/common-htmlawed-settings for common settings.

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

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

Modify the default Panels markup. Use with Fences for ultimate control.