Packing tips and travel prep

I'm off to DC for a few days, and as I've been preparing for this trip, I realized I have a few travel tips to share:

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Packing:

• I travel so often that some things just stay in my suitcase... These three "kits" make traveling a breeze and make packing a snap: 
• "Sleep" kit: contains an inflatable pillow, eye mask, and earplugs
• "Emergency repairs" kit: consists of a couple of band-aids, a safety pin, nail file, tweezers, and a handful each of asprin and pepto-bismol tablets. I rarely have to use these goodies, but when I've needed to, I've been glad they were handy!
• "Shower" kit: which has all of my 3-ounce or smaller travel bottles. The bottles always stay in their tote bag. I just make sure to refill each before heading out the door.
• Back in the days when I didn't rack up so many frequent flier miles, I had a spreadsheet list of items to pack. Before a trip, I'd customize the list. For example, I'd move "scarf" and "gloves" onto the list for cold-weather travel, or add "flip-flops" and "swimsuit" for warmer vacations. Using that list, I never once arrived at my destination without a toothbrush.

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Destination Preparations:

• Investigate the local running clubs (even if it is a work trip) because the best way to see a city is to run through it.
• Solicit restaurant and sight-seeing recommendations from my Twitter and Facebook networks.
• Print a map of the local transit system and a road map to review on the airplane. This reduces those awkward "looking like a tourist" moments wherein I'm standing on a street corner trying to unfold a map the size of a parachute. (I also use my cell phone's map application, but the text on screen is never as clear as a good 8.5"x11" sheet of paper.)

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What item is on your "don't leave home without it" list?

What types of background research do you do about your destination?