C#
Books
C# 5.0 in a Nutshell can help you get started on some of the more advanced topics related to C# and .NET development.
Online Resources
Code Project provides a plethora of tutorials and sample code for C#/.NET developers.
.NET Rocks is an audio podcast that keeps up with the latest in .NET news and interviews successful .NET software developers.
Stack Overflow is a Q&A site with thousands of software development questions and answers covering C#, .NET, and many other technologies.
W3schools provides a SQL reference and tutorials.
Tools
ILSpy allows you to browse assemblies and decompile IL code back into source form.
LINQPad is a useful scratchpad for rapidly testing C# code without the need to put it into a project before testing.
scriptcs allows you use C# as a scripting language rather than creating full-fledged Visual Studio projects.
Other Platforms
Mono provides the necessary software to develop and run .NET applications on non-Windows platforms.
Xamarin makes it possible to develop iOS and Android applications using the same C# and .NET source code.
Class Slides
Session 1 - Overview of .NET; Introduction to Visual Studio; Designing a Form; Object-Oriented Programming; Making the Form Do Something
Session 2 - Data Types; Control Structures; Debugging; Methods and Parameters; Events and Delegates; Exceptions and Validation
Session 3 - Arrays and Collections; Dates and Times; Strings
Exercises Solutions
Session 4 - More Form Controls; Multi-form Projects; Debugging an Application; More Object-Oriented Programming
Exercises Solutions
Session 5 - Indexers; Delegates and Events; Operator Overloading; Class Inheritance
Exercises Solutions
Session 6 - Interfaces, Generics, Database Programming, ADO.NET, Creating DataSets, Using DataSets
Exercises Solutions
Session 7 - Handling Data Errors, More with Data Sources and DataSets, Creating Data Access Objects, Bonus Content (IDisposable), Menus, Toolbars, and Status Bars
All class samples can be downloaded here or browsed on GitHub.