Last year, I planned an event for both sections of my Developmental Psychology course, which is about 60 people. Trying to find the time when the most people could attend was made easier by using a free service called Doodle. It allows you to choose potential meeting times. Then gives you a link to send out to the people you would like to attend. When they visit the link, they can indicate which of the times are best for them. As you can see below, it looks like Monday at 6PM is the best time for a movie night. Doodle also supports making quick polls, and neither you nor your students have to create a Doodle account to use the service.
Doodle Times
Doodle looks like a great tool, thanks for the link.
Something similar that I use all of the time for scheduling things with other Gustavus community members is the Gustavus Google Calendar “Check guest and resource availability” feature.