Websites
Catechism of the Catholic Church
Want to know what the Catholic Church really teaches? This is it, right from the horse's mouth, free on the Internet
Why I'm Catholic
Has tons of great stories of people from many different Protestant denominations and world religions joining the Catholic Church
New Advent
Has the Summa, Church Fathers, and Bible online in a searchable form; also updates with links to the best Catholic blog posts and news stories
Christian Classics Ethereal Library
A digital library of hundreds of classic Christian books, Protestant and Catholic, ancient and modern
The Church Fathers
Has lists of quotes from the Church Fathers assorted by topic
Catholic Answers
Tons of great essays that explain and defend the Catholic faith
Called to Communion
Very well-done, thoughtful essays by converts to Catholicism from the Reformed tradition
Shameless Popery
I had originally decided not to list blogs here because the list would just be endless, but I must list this one because it is so great. It gets a new post almost every day and is always extremely well reasoned and written.
Books
Bible (Revised Standard Version, 2nd Catholic Edition)
The first thing that anyone anyone learning about the Catholic Church needs is a good Bible that has all 73 books recognized by the Catholic Church.
Catechism of the Catholic Church
Want to know what the Catholic Church really teaches? This is it, right from the horse's mouth, in book form from Amazon for only $8 (also free on the Internet, see below)
Four Witnesses: The Early Church in Her Own Words
Written by an evangelical convert to Catholicism, tells the story of the first two centuries of the Church through the lens of St Clement of Rome, St Ignatius of Antioch , St Justin the Martyr, and St Irenaeus of Lyon and shows that the early Church was the Catholic Church; makes the early Church Fathers very accessible to the average person
The Mass of the Early Christians
Tours the worship of the earliest Christians primarily by arranging quotes from early Christian sources by topic, and shows that their worship was Catholic
Early Christian Writings: The Apostolic Fathers
Collection of early Church writings; although I didn't agree with all of the editorially comments, it makes these early Christian writings very accessible
DVD
Catholicism by Fr Robert Barron
This 10-part series is a compelling, engaging, and beautiful explanation of the Catholic faith