I have been reading The Blind Watchmaker by Richard Dawkins. It's a fantastic exposition of the idea of evolution. It came out in 1987, and suffers a bit from describing DNA using a lot of IT metaphors that have dated badly. His state-of-the-art example was the Macintosh II.
Nevertheless, I was blown away by this DNA fact - cows and peas share a gene (probably many genes) called Histone H4. The gene is 306 characters long in cows, just very slightly different in peas (304 characters). The position of the characters is exactly the same (except for the 2 missing characters).
Somwhere about 1.5 billion years ago, there was a common ancestor of cows and peas (and Paris Hilton - I have thrown her in to make it bang-up-to-date). After approximately 20 billion generations, its varied offspring still contain the same DNA data reproduced at better than 99% accuracy. Is that staggering or what?