FFXI has something like this.... http://www.ffxiah.com/shouts

Which I would not mind at all. However, that is not officially sanctioned, and is as a result of some ingenuitive third party applications. An official hub for shouts would be pretty great. Or even just a separate sever wide chat "channel" dedicated exchanges/events.

As much as "content finders" are fantastic and all that, the reason why few people use them is because the current difficulty of the game thus far requires people not only of sufficient level, but of sufficient skill/gear. Unless content difficulty takes a huge dive in ARR, there will still be no replacement to simply shouting for experienced players. Part of the problem, of course, is the powerleveling that creates level 50 characters with no actual skill. If level could actually be an indicator of player skill... then content finders would indeed be truly useful.