Zoho Desk - Industry's first context-aware Helpdesk Software
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
ZenDesk - Zendesk is a beautiful, lightweight help-desk solution.
LiveAgent - LiveAgent is a fully-featured web-based live chat and helpdesk software. It harnesses the power of a universal inbox, real-time live chat, built-in call center, and a robust customer service portal. Start your free 14-day trial today.
Front App - multi-channel inbox service for collaborative teams
Salesforce Service Cloud - Service Cloud integrates customer service with social networks and provides a self-service customer portal and knowledge base system.