Today's 50% off Deal of the Day from O'Reilly is Developer's Guide to Collections in Microsoft® .NET
"Put .NET collections to work—and manage issues with GUI data
binding, threading, data querying, and storage. Led by a data
collection expert, you'll gain task-oriented guidance, exercises, and
extensive code samples to tackle common problems and improve
application performance. This one-stop reference is designed for
experienced Microsoft Visual Basic® and C# developers—whether you’re
already using collections or just starting out."

I am reviewing this book. Here are my initial comments:
The code is well illustrated by diagrams. The approach is practical. The
code is well commented, however the C# code samples would be better
had they been fully Style Cop compliant.
I am looking forward to reviewing the rest of this excellent book. I
recommend this book to all C# and VB.NET Development teams. I concur
with the author who states that the book is not for learning C# or
VB.NET. It is an excellent book for C# or VB.NET developers to extend
their knowledge of the Dot Net framework.