Behind the Name is a wonderful site which lists several hundred surnames and their meanings.  It also may tell your where the surname is derived from. 
The beauty of this site is that it not only concentrates on Italian surnames but on surnames from several different parts of the world such as Germany, Spain, Greece and Ireland plus much more.  If you don't find your surname in one area I would encourage you spend the time exploring other areas of the site to see if your surname originated elsewhere.  You may also want to check out the section entitled The Most Common Surnames  where it lists the top 100 surnames for many countries.  Again, don't forget to use variation in spelling.