Electromagnetism Subject
For more of a physics-style introduction: "Intoduction to Electrodynamics" by Griffiths. Also, I really enjoy "Principals of Electrodynamics" by Schwartz. This is available through Dover Press for like $20. However, it is also much more of a physics reference. I enjoyed its use of Einstein notation.
For engineering-style introduction, I recommend "Electromagnetics for Engineers" by Ulaby. However the CD that comes with it is a waste of time.
If you want to really get down an dirty, then you could jump right into "Elements of Electromagnetics" by Sadiku, but it may be difficult for an introduction.
I do not recommend "Classical Electrodynamics" by Ohanion. I picked it up because it casts all the math in terms of tensors. It is actually interesting, but unbelievably filled with errors, even the second edition. If a third edition came out, I would consider going back, but otherwise stay away.