Geohacks

A Short History of Nearly Everything by Bill Bryson
The single best book to read if you just want to learn more about the grand sweep of scientific discovery and invention. Highly recommended!

Mercator: The Man Who Mapped the Planet by Nicholas Crane
Mercator didn't just invent the most famous, and perhaps most important, map in history, he also had a craxy, amazing life (did you know he was almost burned at the stake?)

The Mapmakers by John Noble Wilford
The best overall book on the history of mapping, from ancient times to the present. There are some very enjoyable sections showing how map makers actualy go about their craft.

Flattening the Earth : Two Thousand Years of Map Projections by John P. Snyder
As you would expect, quite technical in parts, but also lots of good, non-technical discussion on the pros and cons of dozens of different map projections.

We, the Navigators: The Ancient Art of Landfinding in the Pacific by David Lewis
First persn account of years sailing with Polynesian wayfinders, with clear explainations of Polynesian navigation techniques.

The Practical Surveyor: Or the Art of Land-Meafuring, Made Easy by Samuel Wyld
Reprint of the 1725 classic treatese.

Mr. Beck's Underground Map by Ken Garland
Check out the dozens of variations in the London Underground map, with a look at the graphic design decisions that went into them.