The Catechism of the Catholic Church provides an excellent summary of the Catholic faith, drawing upon the documents of Vatican II and the broader Tradition of the Church. Every Catholic family should have 1 (at least).
The mother-load of Mother Church's digital resources. There are plenty of Encyclicals, Letters, Meditations, News announcements, Homilies, and lots more. However, for the latest, it sometimes helps to know Latin or Italian!
I think "Global Catholic Network" pretty much sums it up. Flash games for kids too.
A Catholic apologetics website that explains and defends the faith.
"Your guide to online Papal and other official documents of the Catholic Church." Note: Not a Vatican website, but pretty awesome (and so much easier to read...).