I've used so many of the ideas on this site, I thought I would make my own humble contribution.
I teach 6-18 year old "problem kids" in Thailand (24 classes a week, don't get me started) so I like to use activities that can be adapted to all ages and it usually helps if the kids don't realise they are learning something.
One game I've been using recently is Bullseye, it takes absolutely no prep, is simple enough for a low level class to understand and is useful to review what the kids have (or haven't) absorbed.
Start by drawing up a three ring target on the board. Label the outer ring 50, the inner ring 100 and the centre (or bullseye) 250. Outside the ring is -50. Split the class into 2-4 teams depending on class size and have them take it in turns to throw a soft ball (or an angry bird) at the target. If the team hits a 50, they have to answer a question to get the points (What time is it? Where do you live? etc), if they hit a 100, they have to do an activity, I find it highly amusing to have a kid run into the next classroom and sing happy birthday at the top of their voices, or shout "I love you" from the school balcony, use your imagination. If they hit the bullseye, the entire team must come to the front and perform a forfeit, i.e. dance Gangham Style, perform a skit etc. The winning team gets to choose a forfeit for the other teams.
Its completely open ended, so you can be as adventurous or as conservative as you wish. The most important thing is to make sure the 50 ring is much larger than the rest, so that they are using the TL as much as possible.
Hope this helps, if you have any other fun ideas for large classes of unruly youngsters up to apathetic young adults, I'm all ears