http://www.cjr.org/tools/owners/index.asp
Hope it helps,
-B.
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John Adams asked:
"Which brings us back to my question, which has as its purpose (one of its purposes, at least) to put questions about the media to quantitative analysis as regards ownership patterns and so on. I probably wasn't totally clear about my request: I'm not looking for someone else's analysis of media ownership, but a simple database of who owns what in order to do my own analysis."