There are a number of great classic cocktail books available these days. Choosing some of the books are dependent on your level of knowledge and how involved you want to get into making drinks, cocktails, etc.
Like Huntsman mentioned, the likes of Dale Degroff, Robert Hess, David Wondrich, Gary Reagan are all great modern personalities in the cocktalian World.
Degroff is a good starting point for beginners, he mentions basic techniques and list a good many classic as well as modern and or updated classics in his books. Robert Hess, is a cocktail enthusiast, not a bartender by trade but a highly knowledgeable individual on history, technique, proper preparation, etc. and his book The Essential Bartender's Guide
is another excellent beginners books with a more researched and expanded section on drink families, techniques, and spirits categories. Both of these authors books are wonderfully decorated with pictures and even if you were illiterate you could appreciate the artistry of properly prepared drinks.
Gary Regans and his book the Joy of Mixology
is another excellent read, it is much more in depth and is fashioned more for someone who is looking into entering bartending as a career. About half the book is dedicated to history, technique, with in depth sections on drink families and gravities of different alcohols along with many others. This book has only drawings relating to equipment and technique.
is regarded as one of the best books on classic cocktails and thier history via his biography on Jerry Thomas who published the first recognized bartenders guide in the 1862. It has some amazing classic recipes but be prepared, many of these suit a different palate then what the mainstream highly sweetened drinks have devolved into. This books is one of my favorites and something that I constantly reference. This is more of enthusiasts book and has only a few reprints of renderings from the late 1800's.
Another one is Vintage Spirits and Forgotten Cocktails
by Ted Haigh aka Dr. Cocktail. Another excellent book that mixes classic drinks with detailed history and an array of pictures. Another choice for a solid standby.
If you are looking to move further away from the modern, The Savoy Cocktail Book
is another great addition. This is considered a masterpiece by many in the cocktalian world and if for nothing else, it is a wonderful Art Deco style renderings throughout the book. You can easily buy reprints online. Another choice would be Harry Johnsons Bartender Manual
this one is another classic book with a fantastic section dedicated to teaching bartenders how to behave and how to serve guests properly.
If you want to look into Tikki era drinks, Jeff "Beachbum" Berry is the man to go to. He has several books out and a website as well. http://www.beachbumberry.com/
As Huntsman mentioned as well, the internet is a great place to search around. I'll list a few sites to get you started:http://ohgo.sh/
These guys also have some great videos of bars/bartenders around the worldhttp://ardentspirits.com/Default.aspx
This is the Regan's website and they list a good amount of drink recipes as wellhttp://chanticleersociety.org/
a forum and wikki for cocktail enthusiasts/professionalshttp://www.liqurious.com/
a compilation of different websites and always has stunning photoshttp://www.amountainofcrushedice.com/
another fantastic website with a plethora of information and stunning photoshttp://www.imbibemagazine.com/
website for the imbibe magazine with recipes and photoshttp://cocktaildb.com/
a great one stop recipe shop