Before You Go." Here's my list. It will always be in the 'How To Travel" category, and there's a printable version at the end.
Itinerary and confirmations. I keep all relevant paperwork in a file folder that I can just slip into my carry-on bag when it's time to leave.
Visas and vaccinations. Check this website well in advance of any exotic international travel to make sure you obtain the necessary visas and vaccinations for that country. It can take some time, so plan ahead. http://travel.state.gov
Mail delivery. Fill out this form to have the Post Office hold your mail, or ask a kind neighbor to collect it in your absence. https://holdmail.usps.com/holdmail
Prescriptions. If you take prescription medication, ensure that you have enough for the extent of time you'll be traveling. Always take prescription medication in your carry-on bag, just in case you get separated from your suitcase.
Call credit card companies. If you're traveling internationally, notify your credit card companies ahead of time so they don't block purchases made overseas. Copy passport and credit cards. Make copies of your passport and credit cards so you have a record in the event that they are lost.
Cash Passport card. If you want to use the public bicycle system in Europe, or buy train tickets with an automated machine, you will need a credit card with a chip and a PIN. Travelex offers a reloadable debit card with the chip and PIN, so you can have access wherever you go. http://www.cashpassport.com
Luggage tags. A lot of suitcases come with "built-in" luggage tags, but adding a colored leather one can help identify your suitcase among the sea of identical suitcases in the airport.
Ship your luggage ahead. I’ve never done it, but having seen suitcases lying in the middle of the tarmac at Charles DeGaulle Airport, I can understand why it might be preferable to checking luggage. This company will pick up your suitcases and ship them ahead of you. Priced according to weight and distance. http://www.luggagefree.com
Wallpaper Guides. Concise content with unique recommendations not usually found elsewhere. http://www.phaidon.com/travel
Knopf Mapguide. Divided by neighborhoods, I find these to be invaluable, especially for the maps. In each section is a map of a specific neighborhood with recommendations for restaurants, shops, and attractions. amazon.com/knopfguides
Lonely Planet Encounter guides. Small guides that present the highlights for every major city. http://shop.lonelyplanet.com
Make your own travel guides. No guidebook or website will contain each and every restaurant, museum, and shop you want to visit. I type everything out from all sources and then arrange on the page by neighborhood, color-coding restaurants in purple, museums and attractions in green, and shopping sources in blue. Print out each neighborhood separately on card stock, and you've got your own personal travel guide to carry with you. You'll not only avoid carrying a heavy load of guides with you, you'll avoid missing anything.
Earworms learning. I download this "rapid learning” audio program from iTunes a few weeks before I go. With the use of rhythm, music, and repetition, the words are literally burned into your brain, and you're off with some basic words. http://www.earwormslearning.com http://www.apple.com/itunes
Lonely Planet phrasebooks. I’ve looked at what's available, and these are the best phrasebooks out there. They’re small (3 1/2” X 5 1/2”) and lightweight, but if you don’t want to carry around the whole book, the front and back covers have the basic vocabulary you need to communicate. (If you don’t want to tear the cover off, copy it before you go.) http://shop.lonelyplanet.com
Make your own cheat sheet. If you're going somewhere where they speak a language that isn't available in a phrasebook, go online and find translations for some basic words and print them out on card stock.[Download a printable BEFORE YOU GO checklist]