Safeword adds a new Field type to Drupal 7: the "Name/Machine Name" combination. This field type can be useful for storing public-facint text and an internal "short" name, similar to the way that Content Type labels and machine names are used in the Drupal administration UI. Safeword also uses the new 'Machine Name' FormAPI element in Drupal 7 to automatically suggest a machine name based on the text entered into the human-readable field.
Why bother using it? Using Token, Pathauto, and Auto NodeTitles, Safeword can be used as a replacement for Drupal's standard "Title" field, allowing content editors to create a visitor-friendly title with a customizable URL-safe "short" version that's used to build path aliases. The short URL-friendly machine name can also be used as a Views argument. Finally, it makes your Content Type administration page just a tiny bit cooler.