Audio Patch Cord Center

I was just thinking how nice it would be to have an audio component that would fit with either a stereo or computer system, the device in question being a sort of audio switching center that would have multiple stereo line-level audio inputs (along with an input selector, so that you only have one input active at a time) and multiple stereo line-level audio outputs. It would be designed so that whatever source is selected for input, that signal would be made available to ALL connected output devices at once and all at good line-level. For example, it could have a couple of stereo RCA outs for cassette decks, a couple stereo-mini outs for computers, a couple of optical outs (for the audio-obsessed among us), etc.

Does anyone here know of such a device, or how hard and expensive it would be to build one?