Well you are at a crossroads. Once you learn the basics then there are a bunch of books that take you from intermediate level (which you should be at now) to advanced level of a specific topic.
Typically after a teach yourself series I can jump over to microsoft press style books and go into a specific topic like windows forms or asp.net or you can go to something like O'Reilly cookbook style books which focus on solving particular problems with the language.
A third option is to go hardcore and get into things like network programming, reporting services, com/dll design, game design etc. Eventually you want to get into all areas of the language just to be well rounded, but go with what you like and see where it takes you.
I like going Teach yourself -> O'Reilly cookbooks -> Microsoft Press -> Advanced topics -> Books on language theory (algorithms and program structure).
But whatever suits you. Look around at your local bookstore and read a few chapters of each book that interests you and see if you can easily make the transition. If you can, then it might be a great book to start the "next step".