I took a look at both Coinut and secondstrade and have been trading at Coinut.
Secondstrade was dismissed because they had some weird requirement that withdrawals had to be to the same address that made the deposit?!? Anyway, it would have required that I create a new external wallet just to accommodate them.
For simple binary options on btc price I'm generally happy at Coinut. It is a brand new site and needs some work, but I trust Mr. Wang is working hard at it, as he reassures in the threads ..
https://bitcointalk.org/index.php?topic=821889.0https://bitcointalk.org/index.php?topic=1073352.0