Optimizely - A/B testing you'll actually use.
AddThis - AddThis free website tools include share buttons, targeting tools and content recommendations help you get more likes, shares and followers and keep them coming back.
Dynamic Yield - Personalization & customer experience management
ShareThis - Grow your audience with easy-to-use sharing tools.
AB Tasty - AB Tasty is an all-inclusive platform for conversion rate optimization, personalization, customer activation, and testing.
AddToAny - Share buttons by AddToAny, the universal sharing platform for websites and apps.