"If you head over to Wolfram Alpha right now and input "flights overhead" into the search box, the site will return all the planes that are currently over your position, their altitude, angle, and slant distance." - Jan Wessnitzer

Another WA disappointment... never seen http://www.flightradar24.com/ ? - Egon Willighagen

@Egon, no I had not come across flightradar24. Indeed, much nicer! - Jan Wessnitzer