Virtual Textbook of Organic Chemistry

Reusch

Here’s an excellent online-only o-chem book, updated constantly. The modular layout is a little confusing at first but soon makes sense. Not searchable, but contains an exhaustive index. Requires either the free Chime or Jmol plugins to use. These plugins allow you to twist molecules in 3D, which makes online books far superior to paper ones. And it’s free!