Have recently found Mastock on the OSX App store.
Cost: $100 and realistically portfolio management, more so than whole of market screening.
However, you can set it up to download 20min-delayed data from Yahoo or Google on a scheduled basis, along with a bunch of other features like news RSS feeds, note taking, trading journaling, etc.
Takes a bit of getting your head around, but lone developer is responsive and it's charting is not bad. The fact you are able to get intraday with only 20min delay from Yahoo, makes it worth the cost, imho.
