Meetings Website

Does anyone know of any good time management or meeting websites? As management majors we are constantly doing group projects and we need a way to easily set meeting times when everyone is available. I heard from a classmate that there are website where you can put in the days/times you are available during the week and the website finds times where all members are free. I would love to use a website like this rather than having to send multiple e-mails to all the members. Any suggestions are greatly appreciated.