Basics:
The James Joyce Centre in Dublin, a source for not only background information and educational videos/lecture materials, but a place to find out about Joyce tours and other such experiences.
The International James Joyce Foundation (IJJF), affiliated with the University of Tulsa
The Zurich James Joyce Foundation, directed by the legendary Fritz Senn.
Specialized to the texts:
An incredible amount of information on the Wake found at the below link:
innegans 
ake 
xtensible lucidation 
reasury
Annotated hypermedia version of Finnegans Wake– finwake.com —Available now on multiple platforms.
Find Joyce reading several selections at the below portion of ubuweb: http://www.ubu.com/sound/joyce.html
The entirety of Finnegans Wake set to music, at http://www.waywordsandmeansigns.com
Genetic Joyce Studies: a particularly useful hub of information, especially for the extensive bibliography compiled and updated by Sam Slote.
The James Joyce Scholar’s Collection at the University of Wisconsin-Madison is a incredible source for both the out-of-print of Joyce scholarship and the indispensable.
From a course taught by Michael Seidel at the University of Columbia, a gathering together of photos pertinent to the people and places of Joyce’s writing and life.
Hypermedia Joyce Studies 