"Doodle helps with scheduling meetings and other appointments. It is simple, quick, free, and requires no registration. Simply set up a poll, send a link to all participants, watch progress online, and finally choose the most suitable meeting date."
"When2meet.com helps you find the best time for a group to meet. It is a free service. A video tutorial is available for additional information/help.
Remember the Milk
"Remember the Milk is the popular to-do list that's everywhere you are: from your phone, to the web, to your Google apps, and more."
"Tom's Planner is online Gantt chart software that allows anyone to create, collaborate and share Gantt Charts online with drag and drop simplicity."
"30 Boxes is a calendar web application that lets you build calendars out of all sorts of information like feeds from Twitter, Facebook, WordPress, photos, blogs, personal calendar data, etc. It summarizes daily appointments and to-do items."
"With Google's free online calendar, keep track of important events all in one place. Share your schedule and view schedules that others have shared with you. Access your calendar from your phone using the mobile browser. Receive event reminders via email or text message."
"Eliminate the back and forth of finding a time to meet. Easily share your availability with anyone. Prevent double bookings and forget about time zones."