Just some points to remember
1) Do not let the developers have access to provably fair, or similar feature of the site. MD was screwed this way because their devs knew the seed generation/could access the adminstration.
2) Be sure to have at least 20 BTC when making a gambling site, if not, you're going to have a hard time making profits
3) Be sure to make it provably fair, anything else(except softswiss etc, but a you said, you need a new idea) might be considered rigged and when the complaints later come, you have no way of proving the site is not rigged

Good luck