Place people with common interests in a group and then remix the groups.
You say, "All those who like classical music (or Chinese food, or jazz, or chocolate, or pizza, or travel, or German cars, etc.) please go to this corner. Then say, "All those who like rock-and-roll (or Italian food, or waffles or Italian cars, etc.) go to a different corner." Once you have the audience in about 5 groups, let them meet each other and share what they have in common. Then, if time permits, you can remix pairs again.