I just went out to see the NASA space shuttle Discovery (on its final mission) and International Space Station transit overhead. I didn’t expect them to be as bright and as clearly visible as they were, especially since there is a bit of cloudy haze. It was pretty spectacular!
Below is a video someone took last year that gives some sense of what it is like, if you missed it (there’ll be another opportunity tomorrow, if you’re in the right area, although not quite as bright).
There are a variety of web sites in addition to NASA’s own that provide information about orbiting spacecraft and other objects that may be visible from Earth and worth viewing.