Quantum Field Theory
I really wish there was some excellent lecture series on Quantum Field Theory on the web. But I have never found one.
However, I have a book suggestion for anyone starting out with QFT. The title of the book suggests that understanding QFT is a genetic predisposition, while simultaneously insulting the reader. Quantum Field Theory for the Gifted Amateur, by Tom Lancaster and Stephen J. Blundell. If you are not overly provoked by jokes and funny pictures when reading about a technical subject, this book is actually quite useful. It deals with the introductory aspects of the subject in great detail in order to make every step transparent. I can highly recommend it!