Information files for each chapter of Ulysses plus other pertinent files can be downloaded from this page. 
Ulysses course outline
Marc A.Mamigonian
Composition History of Ulysses
Irish Historical Notes
Some Useful Links
The Catholic Encyclopedia
Guide to the Opening of Ch. 14: "Oxen of the Sun"

Guide to the Ending of Ch. 14: "Oxen of the Sun"

An article on Oliver Gogarty and Ulysses

Chapter 1: "Telemachus" info

Chapter 2: "Nestor" info

Chapter 3: "Proteus" info

Chapter 3: "Proteus" Guide for the Perplexed

Chapter 4: "Calypso" info

Chapter 5: "Lotus Eaters" info

Chapter 6: "Hades" info

Chapter7: "Aeolus" info

Chapter 8: "Lestrygonians" info

Chapter 9: "Scylla & Charybdis" info

Chapter 10: "Wandering Rocks" info

Chapter 11: "Sirens" info

Chapter 12: "Cyclops" info

Chapter 13: "Nausicaa" info

Chapter 14: "Oxen of the Sun" info

Chapter 15: "Circe" info

Chapter 16: "Eumaeus" info

Chapter 17: "Ithaca" info

Chapter 18: "Penelope" info
The Voice of the Shuttle: an enormous collection of links and online texts related to history, literature, philosophy, etc.
The Century Dictionary: Created in the late 19th century, this was the best English dictionary other than the OED.
Cambridge Center for Adult Education homepage.
The James Joyce Center in Dublin.
James Joyce Portal: a large collection of links to online Joyce resources -- some incredibly useful, some mindnumbingly inane.  You decide which is which.
Dublin history on the net: the biggest and best site of its kind.
A searchable Joyce concordance.
"Joyce Country": An alphabetical index of people and places mentioned in Joyce's works.  Very useful.
Some Joyce audio of interest.
Joyce's Schemas