Finding rental accommodation in Italy?

I’m getting close to starting a new job in Italy, and need to find somewhere to live. Unfortunately, this is turning out to be a lot harder than I ever imagined that it would: I’ve signed up for a few websites with ads for room rentals, and they all seem to be uniformly crap. Even worse, my future employer is being absolutely no help at all in finding me somewhere to live.

Does anybody have any advice to offer? Am I better signing up with an agency, and having them find me somewhere? If so, what are these agencies called? “Immobiliare” are estate agents, but are rental agencies called something else?