After putting in all of that hard work getting your virtual event off the ground, you face the hard truth that you need to get more people in front of your amazing content. There are a lot of traditional ways to acquire audience. You could send out mailers (expensive!). You could buy email lists (spam!). You could put a flier on some telephone poles (tedious!). Or, you could take advantage of a massive amount of personal referral power! Easy wins, right?
Facebook events are quick to set up, come with a bunch of options for configuration and are FREE. Mari Smith has an excellent post about effectively using facebook to promote your events that every event-based marketer should check out.