2 Truths and a Lie
Two truths and a lie is a fun way for a group of strangers to introduce themselves to one another and divulge interesting personal facts about themselves. The object of the game is for the group to guess which is the lie. Every participant must write down or think of two truths about himself and one lie. One person begins by saying aloud all three statements. The group then votes on which is the lie.
Human Knot
The human knot is a true test of teamwork and coordination. This game involves close physicality with one another, so it is best for groups already comfortable with each other. Have all the participants stand in a circle and stick an arm out in the middle of the circle. Instruct them to randomly grab another hand and hold it. Then ask them to stick out their other hand and grab another hand from the circle. The goal is for the group to untie the knot and form a circle, without ever letting go of each other's hands.
Toilet Paper Game
The toilet paper game is a fun way to introduce a prop as part of making group introductions. Pass a roll of toilet paper around the group and ask everyone to take as much as they would need for a 3-day camping trip. After everyone has taken the toilet paper, announce that for every square of paper they have, they will have to reveal a fact about themselves.
Hum That Tune
Even if you're working with a musically-challenged group, "Hum That Tune" is an entertaining icebreaker game that will leave everyone laughing. Write down several popular songs or lullabies and put them into a hat. Have a volunteer draw one of the songs and hum it for the group. Let the rest of the group guess what song it is. Continue going around in a circle until everyone has hummed a song. You can distribute prizes to the person who has guessed the most number of songs correctly. Another variation on this game would be to use movies and have participants quote movie lines.