All the talk lately about skyscrapers reminded me of a site I bumped into a while back (September, 2001 if I remember correctly.) The Empire State Building has a pair of Tower Cams (free registration required) that you can control to get a live view of various sights around New York City. Now there are two ways of getting a view from the top; the ESB Tower Cam or the new TowerVision, which apparently offers streamed video (which I wasn’t able to try because they have no Mac client. Yet.)
I first discovered this site a week or two after 9/11; while you couldn’t see Ground Zero, you could certainly see the smoke coming from it. For weeks and weeks after.
There is a handy view selector that lets you pick specific sights. One of my favorites is the Chrysler Building, shown above all in lights. The cams appear to be situated a story or two above the observation decks, and can be aimed at the decks for sometimes interesting shots of tourists.