Optimizely - A/B testing you'll actually use.
Stonly - Create interactive step-by-step guides
SplitMetrics - SplitMetrics is the A/B testing platform for App Store and Google Play page to discover the most converting icons, screenshots, video, etc.
ScribeHow - Create step-by-step user guides, with a simple click
Chartbeat - Chartbeat shows you real-time traffic to your website and allows you to set alerts for any downtime or spikes in traffic.
Shepherd - Opens quality content you choose instead of Facebook/Twitter