I'll echo what others said and say that Voyager 1 is, while the least exciting, probably one of the most amazing spacecraft we've had, and it's still going. It will be going for longer than people will be around, possibly even after this planet is gone.
http://en.wikipedia.org/wiki/Voyager_1
The distance that it is away from us right now it nearly unfathomable. And it still sends back a signal saying it's there. The farthest man made object away. It will also stay the farthest made man object away unless we come up with some amazing new propulsion technology as right now it is going so fast and is so far that no other probe we've launched or we will even launch will pass it.