Saturn V 3rd stage.

[Matt Decker]

I was wondering what happened to the Saturn V 3rd stage after it was used to shoot the astronauts toward the Moon, after all it wouldn't fall back to Earth so it had to go somewhere.

http://science.nasa.gov/headlines/y2002/20sep_mysteryobject.htm

Maybe we could send a Delta IV to refuel it and use it again?

:study:

 

[Brad]

Most of them impacted on the Moon. I believe one went into solar orbit.

 

[Andy44]

For Apollo 11 and 12, the SIV-B upper stage was slingshotted past the Moon into orbit around the sun, where they remain to this day.

All other Apollo lunar mission SIV-B's were intentionally crashed into the Moon and the impacts produced data for seismic sensors left on the surface by previous landings. This data was used by scientists to learn about the nature of the lunar core.

An object spotted in 2003 passing near the Earth in a solar orbit is believed to be the SIV-B stage of Apollo 12, which hadn't been seen in over 30 years, and which subsequently disappeared again. The color of the sunlight reflected by the object matched the properties of the white paint used on the Saturn launch vehicles.

 

[ryan]

An object spotted in 2003 passing near the Earth in a solar orbit is believed to be the SIV-B stage of Apollo 12, which hadn't been seen in over 30 years, and which subsequently disappeared again. The color of the sunlight reflected by the object matched the properties of the white paint used on the Saturn launch vehicles.

A Japanese Astronomor mistaked to be a new astroid, he named it and all then he found out it was just Apollo 12 SVIB. Theres a video somewhere of someone talking to Al Bean about it, he couldnt stop chuckling.

 

[tblaxland]

Pretty good list on Wikipedia:
http://en.wikipedia.org/wiki/S-IVB

 

[Andy44]

http://en.wikipedia.org/wiki/J002E3

J002E3 is the designation given to a supposed asteroid discovered by amateur astronomer Bill Yeung on September 3, 2002. Further examination revealed the object was not a rock asteroid but instead the S-IVB third stage of the Apollo 12 Saturn V rocket[1].
When it was first discovered it was quickly found that the object was in an orbit around Earth. Astronomers were surprised at this as the Moon is the only large object in orbit around the Earth[2] and anything else would have been ejected long ago due to perturbations with the Earth, the Moon and the Sun.
Therefore it must have entered into Earth orbit very recently, yet there was no recently-launched spacecraft that matched the orbit of J002E3. One explanation could have been that it was a 30-meter wide piece of rock, but University of Arizona astronomers found that the object's electromagnetic spectrum was consistent with white titanium dioxide paint, the same paint used by NASA for the Saturn V rockets. Back-tracing its orbit showed that the object had been orbiting the Sun for 31 years and had last been in the vicinity of the Earth in 1971. This seemed to suggest that it was a part of the Apollo 14 mission but NASA knew the whereabouts of all hardware used for this mission; the third stage, for instance, was deliberately crashed into the Moon for seismic studies.
The only other explanation was that it was the S-IVB third stage for Apollo 12. NASA had originally planned to direct the S-IVB into a solar orbit, but an extra long burn of the ullage motors meant that venting the remaining propellant in the tank of the S-IVB did not give the rocket stage enough energy to escape the Earth-Moon system, and instead the stage ended up in a semi-stable orbit around the Earth after passing by the Moon in November 18, 1969. The Apollo 12 S-IVB eventually vanished.
It is thought that J002E3 left Earth orbit in June 2003, and that it may return to orbit the Earth in about 2032.