Beagle - 1:51 pm on Sep 18, 2006 (gmt 0) [edited by: Beagle at 1:52 pm (utc) on Sep. 18, 2006]
econman's example of Amazon is interesting, because a lot of the "community"-type stuff they've tried lately hasn't taken off, such as giving each product its own Customer Discussion Board and ProductWiKi. (And from what I've seen, "not taken off" is putting it mildly - more like unused.) I'd agree that the things that have worked there, such as customer reviews, listmania, etc., work out of loyalty to a product or a niche (or unhappiness with a product) more than to a sense of community - you know your opinion will get a lot of eyeballs if you post it there.
[edited by: Beagle at 1:52 pm (utc) on Sep. 18, 2006]