Let me start off by confessing that I haven't read Ulysses by James Joyce. OK, now that I've unburdened myself, let me tell you about an annual worldwide literary party that takes place on June 16th: Bloomsday.
This is an unusual event -- it's not celebrating an author's birthday; it's celebrating the day that the events of Ulysses unfold. The whole book covers just one day. "Bloom" is the last name of the main character, Leopold Bloom, in case you were wondering, "Why 'Bloomsday'?"
You can read about events taking place in Ireland, New York City, and dozens of other places. The New York Times has an article about it.
A Bloomsday poster for a mock folk operetta (?) inspired by Ulysses: