I was browsing the NYCBigApps competition site and noticed a couple of housing apps. Although they seemed to aimed towards those seeking apartments and may not be entirely accurate, they could be useful for NYC apartment dwellers who want a quick glance of outstanding violations.
NYHousing.info
There's also Stable Rents though this may be more of a rant than a genuine app since it doesn't seem to have a working link to a developer's website.