Shakespeare's Twelfth Night, Form, Structure and Language - An essay by Jenia Geraghty, showing how Shakespeare's choice of form, structure and language shape meaning - http://www.literature-study-online.com/essays/twelfth-night.html
Annotated Twelfth Night - Scene-indexed, searchable, and annotated. - http://twelfth-night.info
Titles from Twelfth Night - A listing of play and book titles taken from Twelfth Night. - http://www.barbarapaul.com/shake/12n.html
Twelfth Night; or What You Will - University of Virginia's electronic text center. - http://etext.lib.virginia.edu/toc/modeng/public/MobTwel.html
William Shakespeare info: Twelfth Night - Full text, plot summary, first performances, and quotes. - http://www.william-shakespeare.info/shakespeare-play-twelfth-night.htm
MIT: Twelfth Night - Scene-indexed HTML of the complete text. - http://www-tech.mit.edu/Shakespeare/twelfth_night/index.html
Literature Network: Twelfth Night - Scene-indexed HTML of the complete text. Summary, search feature, and author information. - http://www.online-literature.com/shakespeare/12night/