UPDATE: Have added Table of contents (TOC) only option that hides next/prev navigation and submitted patch to Moodle Tracker at https://tracker.moodle.org/browse/MDL-36874
If you visit the Open University OpenLearn website at http://openlearn.open.ac.uk and enter one of the courses the materials are presented sequentially with text based links for moving between them. I am not sure if they use a modified book or a custom module for these materials but the navigation is very similar to that of the Moodle Book module.
I have hacked the Book module (Moodle 2.3) to include a new option to choose between the default icons or text based navigation. Demonstration in the video below. If you want to try the code on a test server then it is available (do not use on a live server as it modifies a core table in the database!!!) from https://github.com/brum1975/moodle-mod_book