Here are a few interesting blog posts.

Eric White's Functional Programming Tutorial is a few months old -- I've been through this one a few times, and I'm still finding things to think about when I go back to it.

The Entity Data Model 101: Part 1 and Entity Data Model 101: Part 2 are also packed with good information over at the ADO.NET team blog.

Last, but not least, there's an interesting point of view on how Books Online is created on Buck Woody's blog.