I stumbled upon this last month and many are probably aware of it. It tells you when the ISS will be visible over your city. I have found it notifies me 2-3 times per month when the space station is visible . It gives you the direction it can be seen and the direction to which it is headed. Often the sitings are 2-3 minutes. I have found the best sitings are those that lat the longest and are high on the horizon. Last week there was a 5 minute siting starting 72 degrees above the horizon. All I do is use the compass on my iPhone to track the direction and once you know the time it is instantly visible
http://spotthestation.nasa.gov/sightings/
http://spotthestation.nasa.gov/sightings/