Where I live now is right next to several shopping centers and car dealerships, so few satellites are bright enough to see. A few however, ISS and Iridium flares in particular, are so bright I've just randomly seen them several times when I just happened to be outside, or even in my car.
Some of the best things I've seen:
Launches from Vandenberg air force base right after sunset leave a spectacular smoke/vapor trail lit up by the sun. I haven't seen that for years unfortunately - they usually launch at 2am lately, like the NOAA-N launch recently. (The solid rocket engines from night launches are sometimes visible. The only things big enough to see during daytime were Titan 4s.)
During the one of the Shuttle-Mir missions years ago, I once saw the space shuttle, Mir (both very bright) and a Soyuz following each other across the sky.
I saw the malfunctioning spy satellite USA-193 a day before it was blown away. Fast and bright.
I saw Columbia directly overhead at a lower altitude than usual. It was overcast, but it was so bright I still saw it easily.
I saw space shuttles reentering from 28.5 degree orbits a few times. They looked much like one of the distant airliner landing lights I see so many of on the horizon, but moving 10 times faster and leaving a faint smoke trail (in the middle of the night with no moon, no less - how was it visible?)
