The creators of S. made promotional videos and social media accounts such as Twitter to publicize the book, as well as several websites and blogs that try to decipher cryptic clues within the text.
Before the book came out, a countdown site was created to garner anticipation for S.'s release.
There are two promotional Twitter accounts for both Eric and Jen, in which they tweet margainalia to one another. It is as of yet unconfirmed whether or not the accounts are official. They each are each other's sole followers as well.
An official online radio station, known as Radio Straka, has different stations to tune in to which play both music and talk radio.
WhoIsStraka takes clues from the book as well as real world clues and speculates on what the next step will be for S. Justin Garver has created a detailed timeline of the events that take place throughout Ship of Theseus as well as in the lives of Jen and Eric.
SFiles22 has information on the codes found throughout the book, marginalia, inserts, etc.