In the past I've relied on Dorling Kindersley's excellent Eyewitness Travel Guides; the London guide in particular was extremely well-done. I knew that I would not want to tote around a heavy book with me this time around, and because I was just hitting the major tourist attractions, DK's compact Top 10 Paris book worked just fine for me; although if it's your first time, I'd recommend Rick Steves' Paris. Those of you with iPods can download his Paris walking tour podcasts for free. A friend of mine told me about the podcasts, and they proved to be perfect for places like the Notre Dame, the Louvre, and Versailles.
Other books I found useful:
Where to Wear Paris 2006-a great little guide recommended by one of the gals on The Purse Forum. Essentially a Zagat guide for shopping, but better. If you just want to hit the well-known spots, then this is not worth the investment since you can easily look up address information for those shops on-line before you head out (assuming you're so inclined); if, however, you're interested in specific types of shops for the home or mens clothing that are a little off the beaten path, then this guide is for you. In addition to covering well-known stores, the guide is organized by category and gives the nearest Metro stops for each store mentioned as well as opening/closing hours. Not sure if it's published annually as the 2007 guide was not out in May of 2007.
Zagat Paris Restaurant Guide for obvious reasons
As previously mentioned, I relied on Lonely Planet's French phrasebook; in addition to commonly used phrases, they throw in some amusing ones covering relationships like "what's your sign?" that you can go through for enjoyment while passing time on the plane.
The most useful maps turned out to be the Pocket Pilot Map and the Map Easy; refer to my earlier post "Prepping for Paris: The Maps" for descriptions. The Pocket Pilot Map was compact and a lifesaver if you plan on using the Metro.
Next: the Paris Address Book and Travel Essentials