[smegger001]

You could probably cheat with the one time pad and use a book as a key, pick a pre determined starting point go diagonally down accross the page convert the letters to numbers and xor that against the message. It would be near enough to random and less conspicuous than a pad of random numbers when searched.

[teeray]

That feels like something that could suffer from frequency analysis.

[ted_dunning]

It's called a book cipher and it is definitely subject to various statistical attacks, especially if you have a list of almost all books.

[smegger001]

You could probably do something to increase the apparent entropy like xoringing it with an irrational number like tao or pi starting with a digit determined by the date.