What "extra" item do you never get on the plane without?

Handwipes. Chewing gum to equalize inner ear pressure.
Ear plugs. 6 oz or less TSA approved amount of Eyewash.

P-a-s-s-p-o-r-t. People on this very board have gotten to the airport and realized they didn't have their passport. OR, they waited until the night before to 'get it'; unfortunately, it was either not where they thought it was, or it was in a safe deposit box at the (now closed) bank. Ouch. Plane tickets, and other tickets/reservations for within Europe (or wherever) for trains, hotels, museums, etc. Chargers for electronics. Batteries. Medicines (and several days extra supply - including your type of birth-control, if necessary), and just a general medicine kit - several days of decongestant, aspirin, allergy, Imodium, etc. Any toiletries that would be difficult and/or time-consuming to replace there (special acne cream that doesn't actually cause your skin to break out, special hairbrush that works for 'your' hair, Monistat 7, etc.). Pocket packs of tissues for bathrooms, etc. Inflatable pillow for airplane/train. iPod, too - charged. Food for airplane...sometimes, boarding is delayed or they sit on the tarmac for a few hours...empty water bottles (I choose disposable plastic for weight). Eyeglasses. Credit cards/debit cards. Be Sure and bring the credit card you purchased tickets with (airplane, train, museum)! Patience. And while this isn't a 'take-with-you' item, be sure to arrange for pet-sitters, house watchers, hold mail at post office, pay bills, etc. This topic came up recently (this spring/summer)(and comes up with some regularity), but I can't find it anywhere...I've probably overlooked it. Perhaps someone else can find it. It was an exhaustive list...

Burton, I would categorize at least some of these items more as do not forget essentials, rather than "extras". When packing my carry-on and those items carried on-person, I choose items on the basis of "worst case scenario" (ie: if the flight is delayed, if the airline "misplaces" my checked luggage, etc.). An abbreviated list of the items that I consider essential: > Passport > Medical Insurance documents (WON'T leave home without these!) > IDP & Hostel membership card (even if I don't plan on driving, I pack along a current IDP anyway, for "just in case" situations) > DSLR Camera kit (there's no way I'll check that) - this kit includes Chargers and Plug Adapters for all my electronic gear (these don't take up much room or weight and fit comfortably in an outside pocket). > Cellphone > iPod Touch - really nice to have music to listen to on the flight if there are no movies that interest me. Also works well to access the net quickly to check flight delays or whatever (Netbook takes some time to start up). > Netbook & Charger > GPS (it's safer taking this in carry-on, as less likely to be "lifted") > Compact Medical kit: Bandaids, Analgesics, No Jet Lag med's. > Wet-Wipes (portable, resealable travel package) - I've found these useful on so many occasions! > Backup toiletries kit (Shaving gear, Toothbrush, etc.) > Backup clothing kit (underwear, socks) and of course..... > the 3-1-1- pack While the list changes a bit each year according to trip specifics, these are some of the items I pack for every trip. It's always a "work in progress". Happy travels!

Maybe not a necessity, but a terrific convenience: Purex sheets for laundry. They are dry so won't take up room in your 3-1-1 package. Cut larger sheets into smaller pieces so you can use little bits for sinkloads. Second the vote for tissue packs. Toilet paper is sometimes absent and I used Wet Ones in individual packets to clean a lot of toilet seats. Depending on location and season, mosquito wipes in individual packets. Flashlight in case of loss of power, or walking down a dark street. Lots and lots of Ziplocs in various sizes from snack to 2-gallon. You can buy the two-gallon size online and they make great laundry bags and can be compressed by squeezing the air out to save space. A small scissors (I like a folding one) to cut the moleskin into pieces to fit your owies. (TSA allows up to a 3-inch scissors.) Happy travels!

Some things I've found to be helpful to carry with me: Rubber bands- I like to keep my cash wrapped around cards wether in my pocket or money belt. Sometimes they'll break so always carry a couple extra in the backpack. they've also been handy for other things. Small flashlight for areas (churches & other sights) that may not be well lit. Used it quite a bit in Rome. Binoculars. Small handtowel- more for those hot sunny days. You can always grab one from your hotel room. Chewing gum - While you can get it here in Italy it won't be Big red, Juicy Fruit etc. Any type of batteries - triple A's etc. They're expensive here and don't last long. A small, batterie operated alarm clock. Alot of hotels won't have 'em and don't depend on a wake up call.
For smokers - Bring your own smokes and lighters. cig's are pretty expensive and 100% of the lighters I've bought have crapped out after a couple of days

I took No Jetlag pills and I think it really helped me not feel so crappy when I arrived in Rome after a 10 hr flight from LA and an unexpected 4 hr layover in Heathrow, then another 2.5 hr flight to Rome.

Spare glasses. You need the eye wash, trust me on this. Its a volcanic region with ash that gets kicked up sometimes. Can you say Eye Wash in Italian after you have found a pharmacy that you really can't see or read your crib phrase sheet from? Eyewash; not just eye drops...

I like to wash my face at night using a wash cloth & hotels in Europe don't seem to have wash cloths so I take my own. I use the ones that are dry towels about the size of a large pill and when you get them wet then expand into a full-size wash cloth. They're good for one use only so I take 1 for each day of the trip. I put these in my check-through luggage with the exception of a few to use on the flight & for the first few days of the trip in case my luggage were to be lost. Nice list you've got already. I will save this post as a checklist for my next trip! Thanks Burton.

i pack real light but noise canceling headphones are great on the plane whether you are listening to anything or not...

Two days worth of extra clothing in case my checked luggage is delayed or lost. Cash, credit/ATM cards, passport, Internt'l driver's license...anything else can be bought if forgotten. Copies of hotel, car, transportation, museum/tour reservations. Smart phone (for dumb traveler)/iPad. Medications/Travel insurance. GPS for road travel. Adapters/chargers.

Great suggestions above. if you wear glasses/sunglasses-a tiny repair kit a theater light if you plan to attend play or concert a light weight magnifier to read maps flip flops-for wearing to pool or breakfast if you are not ready to leave for the day lots of bandaids in assorted sizes Plenty of Motrin scented candle for room or balconey bubble wrap for the breakable items you buy and yes, assorted sized ziploc bags
locks for luggage that you leave in hotel room

Definitely a change of clothing. I don't know how many times my luggage did not make it with me. Luggage tags on checked bags that has the address and phone # of where we will be staying the first night. Our bags "found us" the next day in Rome.

a small amount of duct tape (I do live in MN afterall). I forgot to bring on my last trip because I was only going to Santa Fe, NM, and of course my sister's luggage developed a rip and I didn't have my duct tape to save the day.