Auto-Abbrev is a package designed to minimize the typing distance to any word in a file. It works as follows:
Determine a list of all words in the file
Sort the list of words by their frequency (most used words first)
Going down the list, select the shortest unique abbreviation possible. This makes the most frequent words the easiest to type, given that they get first pick on abbreviations
Output the list of (abbreviation, word) pairs in the appropriate format for the editor (Emacs only, currently)
It is then the job of the editor integration to make it easy to know the abbreviations. This is accomplished most effectively by visually underlining the abbreviation characters for each word in-line.