Etheroll is one that really disappointed me. I thought gambling was a guaranteed winner, but transaction fees and variance have made it a dud. Also, I had some Centra that collapsed after the arrests of the founders, though fortunately I was able to sell before it totally collapsed.
I think there is still hope for etheroll, its completely at the mercy of the eth network. I still have a decent sized back, the problem is once Sharding comes out it will have lost any first more advantage.
If ever a project needed a community manager its dice