Get a small ball. A light foam rubber ball is perfect.
Tell them "when somebody hands you the ball, do these things"
- Thank the person who gave it to you, by name.
- Say your name, what you here, and one thing about yourself.
- Hand the ball to another person, if possible a person you don't know.
- Each time you get the ball, you have to say a different thing about yourself.
Keep going for a while. Then say, "if you haven't had the ball yet raise your hand", and finish the game.
This is fun. People need to listen... because they need to thank somebody by name. It makes people try to remember each other (to avoid repeats). It lets less memorable people have more opportunities to say something about themselves. And, it's quick.
If you have to break up into subgroups, ask people to count off in sequence 1 /2 / 3 etc, then go to those groups. That way your subgroups have a better chance of containing strangers.
Example.
I'm Adam Jones, and I'm an analyst in finance. I'm a Buffalo Bills fan.
Thanks Adam Jones, I'm Beth Robinson, and I'm a programmer. My nephew is studying in France this year.
Thanks Beth Robinson, I'm Carole Fernandez, and I drive a delivery truck. I love rock climbing.
(repeat) Thanks Carole Fernandez. I'm Adam Jones. I'm an analyst in finance. My wife and I volunteer at a homeless shelter once a month.
etc etc. you get the idea.