According to Phil Plait of Bad Astronomy you can see details when the ISS flies overhead with a decent pair of binoculars, but with an 8-inch reflector telescope and a decent video camera set up for astrophotography you can grab yourself a Youtube clip…in broad daylight:
I’ve seen the ISS fly over a couple of times on a clear, dark night, it’s quite an astounding site, especially knowing that it’s only 350 km above you when at it’s at its closest. Bizarrely, the second time I saw it I was on a camping trip with family and friends and remarking on what a fascinating sight it is, when it appeared. Happened again the third time I saw it from a pub garden. I wonder…is it alcohol induced?