One of my friends recently gave me "Effective C#" by Bill Wagner. I just wanted to do a quick post to say what an excellent book this is.
I have recently moved from Java to C# and because the languages are so similar I can often do things in C# exactly the same way as I did them in Java but that isn't always the best way. This book explains what those better ways are.
Normally in a book such as this I would find myself disagreing with many of the recommendations, however Bill Wagner does a great job of explaining why he is recommending what he is (sometimes delving down into the IL to show you what he means). This means you can understand when that tip should and shouldn't apply.
I recommend that you get this book and skim through the tips one day when you have some time (I did it on a train). Then when you are next writing some C# you will remember the tip and can go look up exactly what he was talking about.