Zendesk - Zendesk is a beautiful, lightweight help-desk solution.

Influitive - Influitive helps companies increase customer lifetime value and accelerate sales with the power of their own customer advocates. Inspire your customers to stay longer, share their experiences, and attract new business.

Freshdesk - Freshdesk is a cloud-based customer support software that lets you support customers through traditional channels like phone and email, social channels like Facebook and Twitter, and your own branded community

Corsica - Corsica is the gamification app built on Salesforce for Salesforce. 

HelpScout - Help Scout is a simple, straightforward way to provide excellent support

CRMGamified Motivation Engine - CRMGamified Motivation Engine is a gamification solution for Microsoft Dynamics CRM .