Elf on the shelf - order from Amazon or something. Comes with a book.
I think it's very sweet. I subscribe to the notion of 'just move the Elf'.
There's not a hope that I have the time to do elaborate Elf on the Shelf gimmicks for 24 days straight. I do it occasionally but mostly each night we just move it - hang him on a door nob, place him in Christmas tree, stick him in the fridge, put him inside the box of Weetabix, sit him on a chair, put him on the stairs, put him inside a shoe, inside kids wardrobe, in the bath etc etc.
If kids say 'oh but X's elf had the flour out and did xyz' - I reply, he must be a very naughty shelf, I'm glad our elf visitor has better manners than to make a mess ;-)
Ours has an elf door that is stuck on a skirting board (can't get the bloody thing off!!). So we say that the elf put the door their the first Christmas and to check if he came we sprinkle glitter down on the night before the 1st. Kids run down to check if glitter is on the floor on 1st December and then when they see there is - run off to find him.
Oh our Elf also writes a note, saying hello - missed the kids, so glad to be back, couple of things about the year - e.g and I know X got a gold star for swimming (type of thing) and a goodbye note.
Ours leaves on the 25th, so 26th there's a couple of chocolates left outside the Elf door and the glitter is gone.