I just saw this - I. Howard Marshall's New Testament Theology online for free! I need to stop buying books, there are so many on the web you can read for free.
Here's some other great online reads:
- Pilgrims Progress, by John Bunyan
- Holiness, by JC Ryle
- Confessions, St. Augustine
- Lectures on Calvinism, by Abraham Kuyper
- Desiring God, by John Piper