2000 Years of Catholic Writings
http://www.cs.cmu.edu/People/spok/catholic/writings.html
Baltimore Catechism
http://www.catholic.net/RCC/Catechism/Doit.html
Catechism of the Catholic Church
http://www.christusrex.org/www1/CDHN/ccc.html
Catholic Liturgical Library
http://www.catholicliturgy.com/
Second Vatican Council
http://www.christusrex.org/www1/CDHN/v1.html