One of my favorite books is Framework Design Guidelines: Conventions, Idioms, and Patterns for Reusable .NET Libraries
. There is a lot of good wisdom about creating frameworks and libraries that can be used in daily development. As luck would have it, Brad Abrams and Krzysztof Cwalina have a new second edition that you can pre-order now.
At PDC 2008, Brad gave a presentation on the very subject of Framework Design Guidelines and provided the Powerpoint presentation slides for download. There is not a lot of content in the slides, but it does give you a sense on how the book is written with various points labeled Do and Do Not as well as commentary by various respected developers in the .NET Developer Community.
Download the slides directly so you don't need to register.
Check out the new Framework Design Guidelines book which will hopefully be available soon.