This might help you. I don’t advertise using this system but I’m a publisher for them hence I know the answer and they fully accept gambling sites:
BidVertiser
Don’t ask me for too many details, since as I explained above – I don’t use them for PPC adverts, but if I can help from a publisher standpoint, I’ll be more than happy. If you need to see an example of their adverts, you can find them in Articles published on my site:
Casino Bonus Gambling Articles
Please use PM to get responce faster if any questions.