If you want to have effective advertising for a Bitcoin gambling site - I'd highly advise that you advertise on the forum itself (theymos sells ad space each and every month) which would reach a large number of users - or you could try the much suggested method of a signature campaign alongside bonuses/promotions for users of your site. The best way to get people playing is through word of mouth - so have an interesting game with a nice UI with promotions that people want to be a part of.