Free is always good.
Daniel Paoliello, just posted good news.
Free E-books from Microsoft Press.
They usually give some books away for free. I downloaded a couple of them and they were really good.
Now Linq, Silverlight 2 and ASP NET 3.5 here
More free reading (not only technology) here
Powershell book. The download includes both workshops with all the documentation, demo files and script examples and here
And Developing Rich Experiences using Microsoft .NET Framework 3.5 & Visual Studio 2008 also free (WWF, WPF and WCF)…
My recommendation is to check the Microsoft Press site. There’s always good stuff.