Dudle - Dudle is an online scheduling application, which is free and open source.
StrawPoll - StrawPoll Meetings offers a simple interface to create polls that can be used to schedule meetings. With two simple steps, your next meeting is scheduled in seconds.
FullCalendar - FullCalendar is an open-source JavaScript event calendar.
poll.ly - your perfect partner to gather ideas and opinions in real time
Framadate - Make your polls
TiniPoll - Free online polling platform for remote meetings, lectures, online events, webinars or just for fun.