When I was quite little we would spend Christmas Eve singing carols around the Christmas Tree, make sure we had left a piece of shortbread and a glass of milk for Santa and a carrot for the reindeer, put our stockings under the tree and then hopped in to bed to sleep soundly awaiting the morning.
As I got older we would often go to a midnight church service. But another Christmas Eve event was the local Carols by Candlelight (see Christmas Music post) at the football oval. This was community singing of carols, led by the Salvation Army band, with participants holding lighted candles. Carols by Candlelight evenings are still held in most Australian communities these days, but not often on Christmas Eve - although the original event in Melbourne is to this day held on Christmas Eve.
Of course the Christmas Tree lights were always, and are still, left on all night so Santa can see his way.