It seems that typography books lately come with the added bonus of a companion website. I only knew of two so far...
Thinking with Type (by Ellen Lupton)
Designing with Type (by James Craig, William Bevington, and Irene Korol Scala; now in its 5th edition)
...but now I just saw a link on Design Observer for the 4th edition of the book
Typographic Design: Form and Communication (by Rob Carter, Ben Day, and Philip B. Meggs).
It’s nice to have these resources online, no?