In addition to Ancestry, there's one called (I think): My Heritage. Either one costs nearly two hundred smackers per year. I stick with Ancestry only because it's the devil I know as opposed to the one I don't. One great thing about both sites is the relatively recent addition of city directories.
BK: Speaking of which, see the Hollywood group for a post asking about something on Hollywood Blvd. The guy was using a street number directory from 1973, which I asked about and he posted the link. It's one issued by Pacific Bell. The site is strange (I think it's part of the L.A. Public Library?) and I've yet to figure out how to properly navigate it. The search thing seems hit and miss (it seems to search both street names and people/place names).
But yeah, you'll come up with a ton of "no matches" on the genealogy sites. Or more often, incomprehensibly sorted results. I usually get a few good hits right at the top, then a ton of wrong ones (that even go against my search terms), then if I scroll down through a few pages I might find a few more good ones. Ultimately, there's good stuff there but it can feel very hit and miss.