Just back from a week in Italy, and I found the TIM Internet Start package excellent.
It cost total of €20 (€10 for the SIM card, and €10 top-up). This included €5 credit which could be used for Voice/Text, although my main requirement was for Data. This gave me 2GB, which was fine for a week. I also got 4G access for no additional cost (I think this only applies for the 1st month - but I was only there for 1 week so this was ok). I sent a text message to activate the 4G - not sure if it would have worked without this.
Very good experience in the TIM store in Parma - they set me up and activated my service within minutes. They needed to check my Passport - but they seemed to know exactly what I was looking for. TIM coverage seems to be much better than all the other networks. I was comparing with my home country phone which could roam on other networks - WIND & 3 Italy appear to have really poor coverage. I was in some remote areas such as Cinque Terre (coastal villages at foot of cliffs), but always had coverage. 4G is limited to main cities.
Tethering & VOIP worked perfectly.
http://www.tim.it/internet/Internet-Start