This topic has popped up all over the place. You might want to search through both the support forum and the reviews forum. Plenty of info all over those two areas.
However, to get you started:
Books-
Counts, Cuts, Moves and Subtlety - Jerry Mentzer
This is a short book, dealing only with the moves mentioned in the title. You may know certain elements in this book, but the variations to the counts alone makes it a worthwhile purchase. People catching on to your Elmsley Count? This book will teach you many variations to keep your audience guessing. Excellent book at a low price. Definitely worthy of anyone's library.
Card College - All volumes
You may already know most of the moves in the earlier volumes (1 and 2) but the wealth of information inside makes the purchase well worth it. For card magic, I think these books are essential.
Art of Astonishment - All volumes
While not ENTIRELY card magic books, these books have killer material for card magic. Paul Harris has created so many amazing card effects, and you'll find most of them in these three volumes.
Apocalypse - Harry Lorayne - Multiple volumes
I don't own any of these, but I've heard nothing but great things about them. Each volume is said to contain over 200 card effects. There's tons of other magic in here to, not just card work. The only thing that may turn you off is the price ($85 per volume). But, for the amount that they say is in there, it is probably worth every penny.
There are THOUSANDS of books out there. I don't claim this list to be the cream of the crop, but it's certainly a strong start for you.
DVD -
Daryl's Encyclopedia of Card Sleights - If you want to learn more sleights, this series is for you. Hundreds of cards sleights across the 8 (I think it's

volumes.
There are plenty of DVD's as well. Most will focus more on teaching effects rather than just sleights, so I won't list them here. If you're looking for actual effects dvd's, let me know.