At my school we have quite a lot of 'difficult' kids, so are constantly coming up with new ways to solve their behaviour.
One method we have employed at playtime is to have a member of staff (a TA) assigned to a specific part of the playground, where the difficult children are sent to play games initiated by the TA. I.e. children are sent to spend a week on playground A where they are taught how to play together and given ideas for games to play.
In the dininghall we now play popular music to try and sort out the loud, rowdy behaviour while eating.
When the children are travelling around the school with someone other than the teacher, that member of staff is aware that they can award the children house points, or special stickers for their good behaviour. So the children always know their behaviour is going to be reported back, good or bad.
These are just a couple of things we do, if anyone has more to add I would also be interested.