1. Blockchain based new games for gambling platform
2. Decentralized trading platforms
3. Probability of confirmation checker for bitcoin transactions so that bitcoin transactions can be accepted instantly.
4. Decentralized storage
Are few ideas which still need to be developed and this have demand in the market.
1. Nothing good comes from stuff related to gambling
2. BitSquare.io is already in the development process
3. I didn't understand the first part but Lightning network is going to come and the main purpose is to make instant bitcoin transactions
4. MaidSafe is coming too.
Overall , these projects are already under developement and If someone would like to help , Its not by making another similar project but instead help the funding or by reporting bugs on the existing projects.