The granddaddy of all Latin grammar books. Allen and Greenough is the top reference work used by Latin professors in colleges and universities (paid link).
Wheelock's Latin This classic Latin textbook is used in a multitude of college and university Latin courses. It's authoritative--I use it often for it's excellent grammatical explanations. If you use it for self-study, heed my warning: it moves fast (paid link)!
Workbook for Wheelock's Latin This is the workbook that accompanies Wheelock's Latin book (paid link).
A Comprehensive Guide to Wheelock's Latin If you are using Wheelocks for self-study, as I am sure many of you will, this companion volume can really help you succeed. If you buy Wheelocks, take a look at this book on Amazon and see if it might be useful to you (paid link).
Thirty-Eight Latin Stories Designed to Accompany Wheelock's Latin This popular book contains Latin stories that you can read to compliment your study of Wheelock's Latin grammar book. Each story is designed to accompany a given chapter in Wheelocks (paid link).
Oerberg's Lingua LatinThis book is a favorite of most of the Latin teachers I know. It uses the "natural" method. No rules to learn, no paradigms, just a few pictures to show you what the words mean. It's a story about a Roman family. As you go through the story you meet each member of the family and learn about their trials and tribulations (like the son falls out of a tree and gets hurt). I highly recommend this book for supplementary reading (actually, there is a whole series of them) after completing Getting Started with Latin (paid link).
Minimus Pupil's Book: Starting out in Latin This is one of the most popular Latin materials for young children. It's a richly illustrated storybook in which all the characters speak Latin, including the cleverly-named main character, Minimus. The humor here is that the Latin word for "mouse" is mus (paid link).
The Bantam New College Latin & English Dictionary My all-time favorite Latin dictionary. If I were going to be stuck on a desert island and could only take one Latin dictionary with me...uh, well, you get the idea (paid link).
Cassell's Latin Dictionary This is my second-favorite dictionary (after the Bantam dictionary by Traupman). I use it when I need a little more detail about a Latin word. It also has some examples of how the word is used by Roman authors (paid link).
A Primer of Ecclesiastical Latin This book teaches Latin grammar in such a way as to prepare you to read ecclesiastical Latin (church Latin). Our English word ecclesiastical comes from the Greek word ekklesia which means "assembly" and over time just came to mean "church." So ecclesiastical just means "church-related (paid link)."
501 Latin Verbs In this book, each page is a chart showing all the forms of a given verb. An extremely helpful reference book (paid link).
Novum Testamentum Graece et Latine I particularly like this New Testament because it has Greek on one side with Latin on the facing page (paid link).
Biblia Sacra Vulgata The entire Bible in Latin (paid link).
Invitation to the Septuagint A must read if you are interested in the LXX (paid link).
Brenton's Septuagint This is the Septuagint (abbreviated LXX). It is the entire Hebrew Bible translated into Ancient Greek. This is an old edition, but it is inexpensive, has an easy-to-read font, and the English translation in the margin, so it's excellent for general reading (paid link).
An Introduction to Vulgar Latin "Vulgar Latin" does not mean saying something dirty in Latin! It means colloquial Latin - the Latin spoken by the common man.
Mastering New Testament Greek: An Interactive Guide for Beginners I highly recommend this multimedia CD ROM to anybody who wants to learn Greek. I have personally used this product for a long time, and I even recommend it in Getting Started with Latin (paid link).
New Testament Greek Vocabulary I have used these vocabulary CDs for years to build and review my Greek vocabulary. Great for commuters, self-taught students, seminary students, anybody (paid link)!
Learn New Testament Greek This book is a particularly good way to get started with New Testament Greek. It gets you reading right away (paid link).
The Well-Trained Mind: A Guide to Classical Education at Home This is perhaps the most popular homeschool curriculum guide available (paid link).
The Story of the World: History for the Classical Child: Volume 1 This is part of Susan Wise Bauer's popular series of world history textbooks (paid link).
General Latin & Greek Links
Linney's Latin Class This online Latin class for homeschooled and self-taught students is designed to allow anyone to experience a genuine Latin class, complete with a textbook, lectures, and even homework. It's a great way to continue your Latin studies after completing Getting Started with Latin.
Legonium This amazing site uses Legos to teach Latin!
Latinitium This website, run by my friend Daniel Pettersson, contains some truly amazing resources both for beginners and advanced Latin students.
Places to Find Latin Texts
The Latin Library The Latin Library is a huge collection of Latin texts for all to use and enjoy. These texts are in the public domain.
The Packard Humanities Institute This website contains a huge library of Latin texts, and a powerful search feature.
Google Book Search If you select the "Full View" option, you can read and download books on all kinds of subjects including Greek and Latin.
Latin Vulgate.com You guessed it...the entire Latin Vulgate (the Latin Bible) side by side with an English translation.
Corpus Thomisticum This site has the complete works of St. Thomas Aquinas in the original Latin.
St. Augustine The complete works of St. Augustine in the original Latin (and Italian translations, too).