^ Well, since there's no signature campaign maybe you can do your own,,, take advantage of the situation that you will be the only one doing it;)
If you can be allowed to put your referral link in the signature that is. I actually have a lot of signups from my own. So it definitely works.
Mint Dice had their signature campaign running for certain time period. With that they had good visibility among the forum members. Very few go through the different announcement thread and find the best and make use of it. Often if there is some form of contest relative to the gambling site or logo, it'll give more traffic to the platform. Maybe among that little could get converted as revenue.