We have one of the wooden advent calendars which is lovely but I just don't know what I can put in it this year. I did the hairslides/bands and play jewellery last year and I want tod osmething different. Surely there must be somewhere that sells filler packs for these things?
I love the bath pearls idea, DD would love that and now you have said it I realise that I saw some star shaped ones in an M&S outlet for £3.50, I should have bought them! She is also just getting into rubbers, so that would work too. I'm just off to look at that website.
depending on age of children, notes with christmassy activities can work just as well (like snuggle up and watch the snowman, write christmas cards, make christmas shaped cookies ... etc) My girls love it and I think I nicked got the idea from mumsnet a couple of years ago.
Paperchase have lots of small things you can put in. I have a set of minature nativity characters that I put in mine along with a small chocolate. DS then has a minature tree in his playroom to add the nativity figures to as he gets them.