Toothbrush.

Camera

sunglasses

One of those universal plug thingies LOL sorry don't know the proper name for them

Dont forget to say bye to your friends :( LMAO

A supply of any medications your doctor may have prescribed. Oh, yuck, I sound old.

"Traveler's Checks."

Make sure you take a suitcase...don't wanna be carrying all of that stuff in your arms lol...

Don't think anyone mentioned your passport yet. Carry an extra copy in case it gets lost/stolen. You might also want to give someone at home your itinerary/copy of passport in case of emergency. I'd also put a change of clothes in your carry-on in case they manage to lose your bags;)

Less is more...take your basics, clothes that are easily mixed and matched so you can carry less of them w/you, a toothbrush, camera, etc. But remember that you will want to buy a lot of stuff there from clothes to sunscreen or band-aids with the label in a different language on them. Don't worry about forgetting things, too much; if you can find it here you can most likely find it in Europe, it just won't be the same brands that you are used to. Bon Voyage!

All good answers thus far. the one thing that I would not bother taking as they're not really giving you any advantage anymore since credit cards are universal is travelers checks. Just check with your bank and see what you're liable for if your card is stolen. Keep in mind that this does not hold true for debit cards. You lose that, you need to call your bank asap to stop it. Ok so lets see, camera with spare batteries and/or rechargeable, passport and any necessary visas (depends if you need one for a particular country), small first aid kit. Keep a copy of all serial numbers to include photocopy of your passport in a seperate location in your luggage. this will make it immeasureably easier to get a replacement if it's lost or stolen. Also leave copies back at home with someone who will able to be in contact with you if you do run into trouble. Go to the state department website and or google and type in foreign trip advisory. This will be a good starting point to know if there are any issues that you should be concerned with before traveling. I'm sure you don't want to land in a tropical central american country only to find it's in the midst of a civil war. VERY IMPORTANT, make sure the country you're going into does not consider any perscriptions you have as illegal. Just because you got it here, doesn't mean it's not illegal there. already filled out labels for people you want to send cards to. this way you don't have to worry about forgetting their addresses. Get some money exhanged even before you leave the country. Depending on what time you arrive, you may have to wait many hours for an exchange service to open. if it's off hours and it's open, you'll pay through the nose. customs and cultures book or website to check up on the idiosynchrosies of your destination. (take gum to singapore is a $500 fine minimum) do travel light. you can wash what you wear in your room. No one knows you're wearing the same three outfits. Ok, I'm tapped out. I'm sure I'll have more things to add but my brain is fried. The biggest thing is that if you're not going to go back to this place, take a ton of photos. The Marine Corps has brought me to five continents, 23 countries and 47 states. I've got TONS of photos.

Yes, a voltage/frequency converter with the various electrical adapters. Next on the list is buy several almanacs as well as language translation books. Give both away to hotel staff and restaurant personnel. Don't insult Europeans with the translation books but they'll love the almanacs. Asians and Hispanics love learning English. the result being better tips. I used to literally take hundreds with me. Gave them all away and still more would come to me wanting to buy one. I would take their name and address and send them one free later. What they rewarded me with was always much better than money.

take mineral integrators and medicine for stomach problems, don't eat salad and don't drink tap water. Avoid ice. Carefull with the camels, after you have touched them wash your hands as soon as possible and in the meantime make sure you don't put your fingers in your mouth.

The perverbial kitchen sink!

Frommer's book

Whatever you do, remember that many of the electrical outlets in Europe do not work with American appliances, including cellphone rechargers!

Some plastic bags, for laundry, for shopping, for additional luggage when you bring back more stuff than you started with.

Your towel. A towel is about the most massively useful thing an interstellar hitchhiker can have. You can wrap it around you for warmth as you bound across the cold moons of Jaglan Beta…wet it for use in hand-to-hand combat…wrap it around your head to ward off noxious fumes…any man who can hitch the length and breadth of the Galaxy, rough it … win through, and still know where his towel is, is clearly a man to be reckoned with.

put your house in a bag and bring it

Condoms, a Fedora and five pound bag of beef jerky.

A wrap that matches a few of your bikinis. I find I spend a lot of my time waling about with one tied around my dress fashion in the daytime. They save taking a lot of T shirts and shorts and are much easier to just tie around as a cover up.

A shotgun for dealing with those bears!

don't forget your undies!!!

Carry a couple of changes of clothes, especially clean underwear, a few snack food bars, and a small umbrella in your carry-on bag in case your luggage is "delayed" or you arrive during off hours for food/retail services. Make sure to have contact information for your bank, airline, and the nearest consulates handy. Also learn the telephone dialing codes and procedures in advance. Keep your passport and primary credit card on your person, and not in your purse or bag in case it is stolen. Some banks disable credit/debit cards if they see a drastic change in behavior or location on your account. I recommend you call your bank before your trip to have your account annotated in case an alert pops up. I've had this happen many times and it is not pleasant when you need your money right then and there. Other than that, pack very light. The more you carry, the more you worry.

i'd take both cos us girls need to be perpared for everything. this comment was supposed to be on a comment thread,not an answer.so if it doesn't make sense you know why.soz.

Know your atm code by number not letters or words euro atms do not have letters on the keys. At least in Germany they didnt. Bring a watch and/or travel alarm clock. If you dont speak the local language bring a pocket translator or book. The locals will appreciate ANY effort you make to speak thier language, even if done poorly, as long as your intention is good. / Nothing witty, sorry!