Coinut is a bitcoin options owned by Coinut Pte. Ltd., a Singapore registered company. It is the first to provide exchange traded Bitcoin options. Although its current focus is binary options, which are simple for beginners, its long term goal is to provide a full site for both binary and vanilla options.
Although there are already a few binary options sites, few of them are exchange traded, and non of them provide different strike prices, and most of them provide extremely short expiration durations. These make them intrinsically gambling sites as they always have unbeatable advantages to control the chance of winning. Compared with them, Coinut is the only site which supports truly exchange traded Binary options. As shown in their website, they strictly disallow members in the company to trade in platform to ensure its fairness, this is probably the first exchange in the bitcoin community that do not participate in trading themselves. 
Coinut's interface is developed with the goal of maximizing its efficiency and convenience. The core part is written in C++ instead of other slow languages such as PHP (this also makes it more secure). All data is streamed to via WebSocket, which makes the interface extremely responsive and fast.
In additional the the regular methods adopted by existing bitcoin based sites such as SSL, cold-storage, and Linux based server, it is the first to publish verifiable weekly audit information. The purpose is to increase the transparency of the site.
They adopted the proof of reserve audit approach described in this article https://iwilcox.me.uk/2014/proving-bitcoin-reserves. This method generates verifiable audit results and also has been adopted by a few big name exchanges such as Bitstamp and Bitfinex.
However, they move this idea one step further. Instead of relying on a third party, they directly show how much bitcoin reserves they have and how much the total user balance is. The audit is practiced for every week. This removes the necessity of the third party, which users may not trust, and also provide better transparency. The following is a screenshot of their Audit interface.