Cisco Routers for the Desperate, 2nd Edition, by Michael W.Lucas, condenses all you need to know about Cisco routers, and some switching down to a mere 125 pages.
Now your not going to pass your CCIE, or CCNA for that matter, with just this book. The sections covered are quite basic and to the point, but there are many people in the market place, who just have never had any official training on Cisco kit, and this book is for them.
How to navigate an IOS interface, configure interfaces, time, back up configs etc, are covered with a quirky writing style, then a redundancy chapter on BGP and HSRP will start to wet your cisco appetite.
All in all, a good read for anyone new to Cisco kit, or for the plenty of people out there, who did the CCNA course years ago, never did the exam, and now finally get your "hands on", and cant remember the basics!