I have a few in mind:
1)Divide people in few teams (3-4) of 5 to 6. Tell them to remember some details of all other team members .(e.g. Birthday, Fav 5 movie, Most scared of, etc etc ). Then pick up any two people and ask person 1 about all details of person two (person 2 should write it down beforehand

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Or another variation is to find commons (Common 5 fav films, one situation every1 in the team is scared of).
Tell them to come up with team names, and a team action. (like some kinda gesture ) and every1 should do it together .
Ofcourse have a time limit of 3-5 min(max) .
2)Divide people into teams. Have each team divide in two parts. Have two chairs at say 5-7 feet and give them newspapers(lots but limited). Keep one part of the team at one side and another at the other side. Now they have to make a bridge between the separated chairs using only newspapers atleast strong enough to hold a mobile phone without breaking. Catch is , the ground in the gap between chairs cannot be touched. 5 mins should be a good time limit.
3) For the following game you will need atleast 9 - 16 people in a team. Assuming 14 in a team, make a grid of 12 using ropes like this between two poles:
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P | | | P
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P | | | P
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P | | | P
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(P = pole --- and | = ropes)
Now you have 4X3 =12 plus 2(one over and one under the grid) = 14 openings and 14 people. Now the target is to transport everyone from one side of the rope to another rope such that every opening can be used once. Touching the rope while transporting(by anyone in the team) is penalty. The team doing it faster wins.
Give each team 10 mins to come up with a strategy ( like the lightest person should go over the top or enough people should be left at the starting side and enough should be present on the other side to catch the heaviest person in the team).
This is a really really really awesome game.
4) Have a rope (find the right type of rope for the activity) tied between two trees atleast 15-20 feets. The purpose is that every person in the team has to walk from one end to another blindfolded while only two person can hold him. This is also a great stratagy game as people will be divided into holding others, blindfolding the next person(2 blindfolds should be give) as one is walking on the rope stuff like that. Again the team to do it faster wins.
For the above two games you can have the other team demotivating the other team by shouting and stuff when they are playing it.