The total number of Classics Illustrated titles isn't known, as the publications have been going on since 1941 and new titles continue to be released. However, the total amount of titles published is believed to be around 100-200. These titles come in both softcover and hardcover versions, with the softcover usually being available in reprint.
A comprehensive listing and images of the most popular classics, both old and new, can be found on the website ClassicsIllustrated.com. This website allows readers to browse through the titles and covers from all of Classics Illustrated's published books, and provide additional information such as the plot line, illustrations, and reviews.
In addition, a brief history of the comics series, along with a list of the top 20 titles, can be found on MyComicShop.com. This website also contains a link to Nostalgia Merchant, an online store that sells the Classics Illustrated comics online.
For more in-depth resources about this series, you may also want to visit the website of the Joe Kubert Library of comic art, as it has an entire section devoted to the history of Classics Illustrated.