Handbook of Applied Cryptography
cconnell writes "The Handbook of Applied Cryptography is now available free (for personal use) on the Internet. This is a $100 book. Note also the companion C source code for most of the crypto algorithms, written by James Pate Williams. There is some very cool code here!"
The ink cartridges required to print out the some odd 800 pages are worth $100.
For an online resource this is great in case I'm travelling or my hardcopy is unavailable.
However, I still want my bible in print.
Someone you trust is one of us.