Apparently a very good book on ASP.NET MVC 2 is “MVC 2 In Action” from Manning, and while the authors are putting the finishing touches to the MVC 3 version of the book, the entire MVC 2 version is available completely free in Word document form at: https://github.com/jeffreypalermo/mvc2inaction.
Every version of MVC relies on the previous version (except with a few breaking changes), so there is still value in reading this free resource.
Jeffrey Palermo’s original post is here.