i put students into 3 groups (of about 5). i chose 3 vocabulary topics that i wanted to revise - e.g expressions using verb to go / adjectives describing weather / idioms for describing people then gave each team 1 word for each of the these topics on a card - e.g to go down with (an illness) / breezy.
then i gave each group a prop - i used a telephone, a bunch of flowers and a fake skull
i also had a pile of costumes which i allowed them to use whatever they wanted from (but you could also allocate these)
then i got them to write their own plays, which had to include the relevant vocabulary and the prop. - what i didn't do but should have done was to explain exactly what they would have to do before letting them see any of the props and costumes as it was quite difficult to hold their attention after that.
whilst they're writing their plays you should be monitoring very closely, helping them as much as they need, but most importantly noting down grammatical lexical and pronunciation mistakes as this is when they are speaking naturally rather than whilst they're performing - but don't go through these till the very end of the lesson.
give them time limit call outs if you need to hurry them along, then when they're done each group took turns in performing to the rest of the class.
after this we went through the mistakes on the board (they were all feeling ubinhibited so didn't mind having there mistakes pointed out) and also any other things which came up - eg with the telephone things like to pick up, to hang up etc.
you could also try giving them an opening and closing line which they must use, or grammatical structures that you've been doing recently instead of just revising vocabulary points.
i did this with upper-int adults (but it should be fine for intermediate - adavanced, maybe pre-int but i don't have any experience with them, and kids would love it) and it took about 1 1/2 hours, but i could easily have spent more time on it.