Where in Italy are you staying???
I have checked the weather in a few Italian cities and it look like the nights are very cool, some cities ( Venice) are as low as 4C right now. So I would bring some gear to keep you warm in the evenings. WHen the warmer weather somes, you can mail some of your cloths home regular post, that saves you from having to lug them with you, or carry them back with you.
Don't forget to get any perscriptions you might need at home, it just saves you some hastle of having to go to an Italian Dr. to get new ones. Same with glasses perscription, keep a copy of that with you if it applies.
To go out drinking and not look like a travel bum ( like I always do), bring kakies and a dress shirt, that should tide you over for a couple nights out, you might have to spring for a new shirt or 2 while your there. I am more of a cargo/t-shirt kinda guy.
Earplugs for the plane ride, aswell as nights where you might be sleeping in hostels or with a flat mate. Travel sewing kit, I did not think I was going to need one of these either, until I ripped a pair of pants and had to use it ( thanks mom)
Your normal clths and stuf of course, socks underwear and what not.
Condoms, I think your a guy, but even if your not, you do not want any unsuspection proplems after a night of drinking that leads into a torid night..(wink, wink, nudge nudge)
hmmm, some of my favs...baby wipes and hand sanitizer, just hand to have.
Thats what I can think of now anyway, I am sure others will add stuff as well...
to the boards, glad to have you along for da ride!!!