Thunderbird - Thunderbird is a free email application that's easy to set up and customize - and it's loaded with great features!
YArooms - YArooms is a web based booking software package that makes it easy for you to manage rooms and...
Geary - Geary is an email application built for GNOME 3.
BOOKMEETINGROOM.COM - Book Meeting Room - Conference & Meeting Rooms Management
Evolution - Apps/Evolution - GNOME Wiki!
Resource Central - Meeting room & resource scheduling software for Outlook