I'm not one for apps but a mate of mine showed me Flight Radar and I love it.

Yes it's totally anorak and geeky but if you see planes flying overhead and ever wondered where there destination was, then Flight Radar is for you. You'll also get their real time location on a map, altitude, the flight path, where it's come from, type of aircraft etc etc.

If you see a lone sole in the Rumney area looking up into a clear blue sky saying, "Mexico City to Paris, well I never", unfortunately that is likely to be me.