You mean IC advertising?
If so then you will find the Hyldaa, Gug and Oja
Message Boards very useful and well read. You might also consider trying to get some advertisement in the new in game
Guilds & Traders Journal whose recent publication was a very good read; and widely distributed evidently.
One can also pay for GM Posters to be put up. You will see the Champion's Cup advertised in that way.
That's a few that come to mind right away.
- Nova