Over the past several months (years) I've given a series of presentations on the topic of Threading in .NET. These presentations have been to various .NET User Groups, at company 'brown-bag events', or even over Live Meeting. They have been a real treat for me as I love the topic and it's near and dear to my heart. I came across this free e-Book (also available as a PDF) that I would highly recommend to anyone wanting to dig in and learn more about Threading in .NET. The e-Book is written using the C# language, but that shouldn't be a hindrance to anyone wanting to understand the inner workings of the topic.
Enjoy!