Human Knot
The human knot is an icebreaker that will have people laughing and trying to problem-solve at the same time. Don't tell the players what the goal of this icebreaker is until after they're setup. Get everyone into a circle facing each other, then have them grab each other's hands. They should do this in various directions -- across from each other, next to each other, a few people over and so on. To achieve the goal of the game, they have to unravel themselves back into a perfect circle without letting go of each other's hands.
Sardines Game
This reverse hide-and-seek game works best with 15 to 30 people. Choose one person to go hide and have everyone else stay together without seeing where the person went. Once the person is hiding, send everyone off to find him. As each seeker finds the hider, he quietly joins him. Before long, all the seekers will be packed in with the original hider like sardines in a can and keeping as quiet as possible. The last person to find the group is the loser.
Telephone Charades Game
This can be one large group activity or you can have a few smaller groups playing, depending on how many people are in attendance. If you have smaller groups, make them up of six to eight people each. Have everyone line up one behind one another and give a clue to the first person in line, such as "sailboat." That person then turns around and acts out the clue to the person behind her. That second person then turns around and does the same with the next person, and so on down the line until the last person, who has to try to guess what the original clue was.
Zoom
This game has people put together a story from pictures; you'll need one picture for each person at the gathering. The pictures must sequentially tell a story, but you will hand them out randomly. Before giving out the pictures, tell everyone that they cannot show their picture to anyone. Give everyone a few minutes to study all the details of their picture. Once you announce the start of the game, each person has to take a turn explaining to the others what his picture is about. Then, everyone has to work together to put each segment in sequential order to tell the photographic story they were given. They can't look at the pictures until they're done, to see if they got it right.