Zendesk - Zendesk is a beautiful, lightweight help-desk solution.
Cloze - Smarter Relationship Management
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
Accompany - Accompany platform integrates with email, contacts, social feeds and more to keep you informed on your professional connections.
HelpScout - Help Scout is a simple, straightforward way to provide excellent support
Propeller CRM - Small business CRM with deep Gmail integration