RingCentral - RingCentral is the leading provider of cloud-based communications and collaboration solutions for small business and enterprise companies
Roundcube - Web-based IMAP email client
Dialpad - Switch is a cloud-based phone system built for Google Apps users.
Mailpile - Mailpile is a modern, fast web-mail client with user-friendly encryption and privacy features.
Aircall - Aircall is a call center software of a new generation designed for fast growing companies. Setup instantly and integrates to your CRMs
Horde - Horde Groupware is a free, enterprise ready, browser based collaboration suite.