1. Euros--many, many businesses in Italy do not accept credit cards, even in big tourist destinations like Rome and Venice.  Don't wait until you're there to try to get local currency.
  2. A debit card that's going to work--since credit cards are not widely accepted, you will need ready access to cash.  Your bank, however, may suspend your card if they notice unusual activity.  Call them before you leave to let them know you'll be travelling so this doesn't happen.
  3. A cable-style bicycle lock--If you will be traveling from city to city by train, you can lock up your bags and have a leisurely meal in the dining car without having to worry about someone making off with your luggage at the next stop.
  4. Mp3 audio tours--guided tours are a great way to get the most out of your visit, especially since you can ask questions of your guide.  They can be expensive, though, especially if you are travelling as a family.  There are several mp3 audio tours covering various points of interest in Italy that you can download for free.
  5. An extension cord or 3-way splitter--Camera batteries, mp3 players, laptops, PDAs, cell phones...If you are traveling with more than one person, the number of gadgets that need recharging can multiply quickly.  Get more mileage out of your outlet adapters with a splitter.
  6. An extra outlet adapter--If you lose one, you won't have to waste time or money (as much as 10 times what they cost at a discount store) to replace it.
  7. Conditioner & hand lotion--these products, staples in American hotels, are seldom provided in Europe.  If you can't live without them, bring them.
  8. An Italian-English dictionary--Folks always appreciate your efforts to at least make an attempt to communicate with them in their own language first.  And many Italians who speak English are proficient, but not fluent.  A dictionary helps to bridge the linguistic gap.
  9. A handheld GPS--Many writers, guides, and travelers say the best part of enjoying an Italian city is getting lost in the little alleyways and side streets.  Knowing you can get "unlost" any time you're ready can take the stress out of exploring.  Just finished up at a museum and you're famished?  A GPS can list the restaurants near your current location.  Taxi driver doesn't know where you're hotel is?  That's no surprise--they can't possibly be expected to know where every hotel, bed & breakfast, and restaurant is in a big city like Rome.  Show him on your GPS and you're on your way.  An expensive gadget, but well worth the investment if you can afford it, especially if you travel often.  You may need supplemental software to cover Europe.
  10. Patience--In Italy, a meal at a sit-down restaurant is meant to be a relaxed, leisurely affair that allows plenty of time to enjoy food, wine, and good company, and can easily last 2 hours.  With a limited amount of time to see and do everything they hope to, many tourists just want to eat quickly and get back to sightseeing instead .  This disconnect in expectations can result in stress and frustration for both the customer and the restaurant staff.  If you choose a restaurant with table service, be patient and "enter in" to the Italian way of doing things.  You will enjoy your dining experience much more, and come away with a more comprehensive experience of Italy, as well.  If you just don't have that kind of time to invest in a meal, choose a restaurant with counter service, instead.