To start things off I thought I'd plug a cocktail book and a few other web resources.
See, Mix, Drink
This is probably one of the most interesting cocktail books to be released recently. It isn't an exhaustive library of drinks, though, and some of the recipes don't reflect the cocktail revival going on right now (nobody muddles orange into old fashioned or shakes a martini anymore). However, the presentation of each drink as an annotated engineering drawing really works well, and I found myself flipping through each recipe. It makes a great coffee table book, or a book to leave on your bar for people to DIY their own drinks. I have a few books on the shelf above my little bar cabinet, and this is the one most people grab when poking around.
These other three books are definitely worth the purchase, but are already well-reviewed everywhere, so I won't rehash these.
The Joy of Mixology
Savoy Cocktail Book
One of my other favorite resources is smallscreennetwork.com. The site hosts a number of web series by cocktail enthusiasts and bartenders who show off recipes, teach tricks of the trade, and more. YouTube will also yield plenty of cocktail videos, but the guys over on smallscreennetwork really know their stuff. The Cocktail Spirit with Robert Hess is one of my favorite cocktail video series. Anything by Morgenthaler is always great too.
If you're looking to get into cocktails, check these resources out. Oh, and don't overlook cocktails.reddit.com if you've got a related question.