Other sources of proverbs:
Lifeinitaly.com has several pages of Italian Idioms and Proverbs.
Deirdré Straughn's Beginning with I Italian Idioms and Sayings
About.com has a nice article that links to an alphabetical index.
Moving2Italy has an extensive list of links relating to Italian proverbs.
Sinet has a long list of "reverse" proverbs (i.e. Italian translations of English proverbs)
Tutorino.ca has a nice list of proverbs along with how they can teach you Italian grammar
See Neapolitan page for more proverbs in Neapolitan