Here in the US we are limited on the PPC we can do with gambling related opportunities. E-mail is great, but you really need to stick to it for a long time to build a list.
SEO is the way I always go, but I do think there is merit in social media. You just have to make sure you’re doing it right. If all you are doing is pushing a link on people, they won’t respond. If however you help with something they care about, they will help you without hesitation.