I would prefer if we did just billboards around Aladra and docks that you could pay to post map art to on a daily basis. Because everyone will eventually just turn it off, making the feature all but useless as he point of it is to advertise, and you can't advertise to people who can't see your advertisement.
If you right click the billboard, people will get to see a custom message from you advertising if they want more info.
Billboards can also have a reduced price if it's just a colored sign.
But I think the chat feature would be good, if it didn't require spamming of the advertisement every 5 or so minutes. And that's just not fun fun listen to/or moderate. Of course, I may be perfectly wrong, but I shall await for the FoxLad to yell at me once more about how I'm smooth brained and this will work