Hey Jason,
I agree with you that many are just rehashes of the API with simple, almost unusable samples with each. One of the things I liked about Karl's book is that he teaches you not just how to build software but how to build
better software.
As for me writing a book, I'm knee deep in co-authoring a Coding4Fun book actually
The book's content is centered around buildnig 10 fun, cool projects on everything from YouTube, World of Warcraft, the Wiimote and more.
As for a more in-depth book, it depends on what you mean. A lot of the larger books (1,200 ASP.NET page books) only cover each topic in 15 pages, but they cover a LOT of topics, just not deeply. Then there are single books that go very deep, and those are good if you want to know what the heck is actually happening like Jeffrey Richter's
CLR via C#. I'm probably best suited for an applied book with actual projects as documenting APIs to me isn't personaly interesting, but showing how and when to use those APIs in an application is. As for a Richter-type book, I'm not the right person and I don't think I could compete with him anyways
There are a couple of other books that I think the .NET community needs though -
Pragmatic Business Intelligence for Developers - SQL Server 2008 BI using real-world examples like US Census data, Technorati search data, YouTube video popularity, etc.
Simple, Beautiful WPF Designs for Developers - This was a personal pain for me having read multiple WPF books and flipped through several including Expression Blend books - almost none of them show you how to make something attractive. Go to a bookstore and flip through WPF/Blend books and you'll see terrible-looking UIs with big green and red blocks. This book would be a collection of WPF control skins, quick usability guidelines, and instructions for how to reuse and structure them in your applications.
Cheers,
-Dan