This site presents "modern, high-quality on-line textbook on advanced electrodynamics, entitled Electromagnetic Field Theory, free for anybody to download and to contribute to."
"Written with the advanced undergraduate or graduate student in mind, Electromagnetic Field Theory is a textbook on the theory of electrodynamics, at roughly the same level as the well-known textbooks by Jackson and Panofsky&Phillips. The book is written mainly from a classical field theoretical point of view, emphasising fundamental and subtle properties of the EM field and includes a comprehensive appendix on the mathematical methods used. It treats relativistic covariance and the Lagrangian/Hamiltionan formulation of electromagnetic field theory, with an eye on modern ideas of symmetries, duality and unification of theories, and includes a rigorous, comprehensive and detailed treatment of EM radiation phenomena and some elements of semiclassical quantum electrodynamics. ...."