NASA recently announced that Voyagers I and II are now at the edge of Earth's solar system and moving outward into interstellar space.
The Miami University Libraries Government Information and Law Department has several NASA publications from and about the Voyager Project covering it's more than 30 year history.
In addition to expanding humanities knowledge of the outer planets of our solar system, Voyager I and II both carry gold records containing images and sounds of life on Earth. Designed by a team lead by Carl Sagan, the "murmurs of Earth" include:
"...118 photographs; 90 minutes of music; greetings in 55 human languages and one whale language; an audio essay featuring everything from burbling mud pots to barking dogs to a roaring Saturn 5 liftoff; a remarkably poetic salutation from the Secretary General of the United Nations; and the brain waves of a young women in love."
The records were intended to be an introduction from the human race to any alien species that could find and decipher them. Neither of the Voyager probes will pass by another star for about 40,000 years, making it incredibly unlikely that an alien race would find them any time soon (unless of course one of them decides to come home). Carl Sagan wrote the book Murmurs of Earth : the Voyager interstellar record (available in the MU Libraries) detailing the creation of the records. The full contents of the golden records can be found on the Jet Propulsion Laboratory website.