For the last 15 minutes of each one-hour class, I have topic-guided (ie. Family, Hobbies, etc.) Free Talking time in groups of 3 or 4 students. To encourage the students to talk to students they haven't met, I have the students count off. (You know... 1,2,3,4,1...) If I have 15 students and I want groups of 3, I have them count to 5. Then the students group up where I indicate. Ones in the back, Threes in that corner, etc. A benefit of this method is that students are separated from their close friends they sit next to everyday.
Very simple and quick. For variety (and amusement), I have them do The Wave, or some motion. Then the activity begins.
Evan
Kwangju, S. Korea