Field Formatter Class
https://www.drupal.org/project/field_formatter_class
Add a class to a field wrapper.
Advanced Text Formatter
https://www.drupal.org/project/advanced_text_formatter
Extra text field formatting options.
Tag Formatter
https://www.drupal.org/project/tag_formatter
Needs patches, but works well.
Formatter Field
https://www.drupal.org/project/formatter_field
Field for selecting entity display or something?
Field Formatter Filter
https://www.drupal.org/project/field_formatter_filter
Format text fields with another text filter?
Fixed Text Link Formatter
https://www.drupal.org/project/fixed_text_link_formatter
I think this formats link text with a set default instead of by user input.
Custom Formatters
https://www.drupal.org/project/custom_formatters
Advanced php/twig and more formatters. Hard to use/debug, needs patches.
Formatter Suite
https://www.drupal.org/project/formatter_suite
Options for several field types.
Simple Field Formatter
https://www.drupal.org/project/simple_field_formatter
Unsupported D8+ release: https://www.drupal.org/project/simple_field_formatter/releases/8.x-1.0-alpha2