Planning for a trip in advance is FAR more fun than planning for your trip while you're on your trip, sans internet, when you could be swimming in the ocean instead.

Seatguru.com - "Your enlightened guide to airline seating". Check out specific floor plans of specific jets so you can evaluate seat placement and dimensions.

Rick Steves - In Europe Jen and I used "Europe Through the Back Door" and it was really useful. Great tips for being a traveler as opposed to a tourist. He's also got about 100 other books on practically anywhere you'd want to travel, along with a TV show on PBS which is cheesy but full of information.

Lonely Planet - Somewhat similar to Rick Steves', there's a Lonely Planet book for anywhere you'd want to go. The only downside is sometimes they're the heaviest item in your pack.

Eurotrip.com, Your Backpackin' Europe Site - Very useful if you happen to be backpackin' Europe.

AAA - Useful site for planning trips, getting maps, ordering tripTiks, etc.

If you know of a good travel book or resource, please let me know. Thanks!