Online version
http://www.robotwisdom.com/jaj/portrait/
of the novel with some good other links.
Brandon Kershner's Portrait Page.
http://web.nwe.ufl.edu/~kershner/port.html
Probably the best online resource for the novel. Includes biographical information, notes on foreign phrases and allusions, and critical essays. Excellent resource.
Links galore.
http://www.levity.com/corduroy/joyce.htm
Find numerous web resources on Joyce and Portrait.