Roundcube - Web-based IMAP email client
ShareVault - ShareVault provides Virtual Data Rooms for secure document sharing during due diligence and other business critical processes.
Horde - Horde Groupware is a free, enterprise ready, browser based collaboration suite.
iDeals Virtual Data Room - iDeals Virtual Data Room is a tool that provides secure access to large amount of confidential documents and can view, analyze and collaborate in a protected environment.
Rainloop - RainLoop is a web based email client.
Drooms - Virtual data room software