I see this question several times a day from newbie’s to professionals. I have listed the best C# books that I have read so far.

1. ECMA-334 C# Language Specification. – FREE book. This is probably the best place to start. Read it backwards and forwards and you can even request a hard copy.
2. Absolute Beginners Guide to C Sharp 2nd Edition – Used this early on and found it very useful even if its game programming.
3. C-Sharp 2.0 - The Complete Reference, 2nd Edition (McGraw-Hill, 2006) – One of the most useful books that is always with me. It contains short example code and is very well written.
4. Dot Net Zero - Charles Petzold  - FREE book and you should definately give it a read.
5. C Sharp in Depth by Jon Skeet -  Probably one of the most in depth books on C Sharp and definitely not for beginners. Jon Skeet knows C# like no other. I would consider this book the Bible of C#. If you understand 50% of this book, you have a good understanding of the language. 
6. CLR via C Sharp 3rd Edition – I just started reading this book and it is another book thats not for beginners. If you really want to understand the CLR then give this book a try.

Well, thats it. I hope you enjoy the books as I have spent a lot of time researching different C# books.