Something that many girls don't think of bringing are feminine products. I know, it's not the most enthralling topic. Seriously though, it is insanely difficult to find certain brands and when or IF you do, they are very expensive. Especially if you're used to plastic brands, using the old-fashioned cardboard kind is totally uncomfortable and unfair to your lady garden (save that term for your TMI dictionary). I've told all my friends this before coming and they were always happy they did! Of course, you don't want to overload your bag with THAT stuff (imagine the look on the Italian security guard's face if he checks your bag?) so if you know you have parents/family/really good friends coming to visit, have them bring an, *ahem* replenishment.
Also, if you have frequent U.T.I.'s or yeast (ew) infections (are you regretting reading this article, yet?), I highly recommend bringing the medications necessary for those as well. The typical treatment for a U.T.I. in Italy is dropping a dissolvable tablet into a glass of water and drinking it - and let me tell you, it does NOT taste like a milkshake. So, to avoid having to deal with anything more stressful than where you're going for dollar shot night, take the precautions before you treck overseas - you'll be happy you did!