We've had some great stuff recently, if you think about it.
Comets: Hyakutake was easily visible, Hale-Bopp was outstanding, and Shoemaker–Levy 9 _ran into_ Jupiter, leaving damage that was visible to small hobby telescopes.
Manmade: Back when Mir was still in orbit, at times you could see the shuttle chase it down. ISS is fairly bright and fun to watch. If you do a little planning, Iridium flares can be very bright for a minute or so. Go to http://www.heavens-above.com/, and look for upcoming flares at your latitude and longitude.
Comets: Hyakutake was easily visible, Hale-Bopp was outstanding, and Shoemaker–Levy 9 _ran into_ Jupiter, leaving damage that was visible to small hobby telescopes.
Manmade: Back when Mir was still in orbit, at times you could see the shuttle chase it down. ISS is fairly bright and fun to watch. If you do a little planning, Iridium flares can be very bright for a minute or so. Go to http://www.heavens-above.com/, and look for upcoming flares at your latitude and longitude.