If you are looking for some spacey ringtones or computer event sounds check out the NASA Sounds page. You can have such classics as One small step for man or Houston, we have a problem. Sources include the Mercury, Apollo, and Space Shuttle missions, as well as the ISS, and even bleeps and bloops from the likes of Sputnik or the Saturn Radio Emissions. They have MP3 and M4R formats, and include some general directions as well.