Nuages - Nuages is a collaborative meeting poll system..
Let's Meet On - A super simple way for groups to find a date and time when everyone is available.
Framadate - Make your polls
Letsfind - Letsfind is a fast, easy-to-use, ad-free way to create online (meeting) polls.
FullCalendar - FullCalendar is an open-source JavaScript event calendar.
FreeBu - Smart free/busy calendar sharing and meeting organizer.