When writing a formal or business letter, presentation style and format is key to making a good first impression. These templates provide excellent examples of how to structure such a letter, and include sample content to act as a guide to layout.
Basic template for German letters according to the DIN 5008 standard
It is building on scrlttr2, so everything should be pretty much self explaining.
For contributing, see https://github.com/ckuenzle/din5008-letter.