One of my favorite holiday crafts! We've done a bunch.

This year I ordered a pack of 6x6" Christmas scrapbook papers, and we used 25 of them to fold into origami envelopes. We strung those on a string and hung them as a garland from one of our fireplace mantles. The "goodies" inside are a collection of little things, everything from an idea for an activity we'll do together that day (like the day that the town does free train rides and Christmas carolling around town, or the library's tree lighting party, or a service project we have scheduled), to a couple of stickers, to instructions for where to hunt and find a hidden Christmas book to read together, to a pretty gift tag where I've written down something that we can all be thankful for and pray about that morning.
As another one this year, I ordered blank match boxes from Oriental Trading Co. (they call them craft boxes), and covered them in some of the other scrapbook papers, so we have 25 tiny decorated boxes. I'm finishing gathering together a collection of mini treats to tuck inside the boxes (again, very inexpensive and simple -- two beads that we'll use to make necklaces that day, two jellybeans, two stickers), and I have a dozen different ideas about ways to display them. I looked around the web for inspiration and found LOTS -- some different types of matchbox advent projects are here:
http://kiddley.com/2006/11/22/fill-y...ith-activitieshttp://www.bhg.com/bhg/story.jsp?sto...8229594673.xmlhttp://lostbuttonstudio.blogspot.com...-calendar.htmlhttp://www.marthastewart.com/portal/...RD&rsc=relatedhttp://www.flickr.com/photos/44135464@N00/2051313219http://flickr.com/photos/10806782@N08/1368216154/http://www.marthastewart.com/portal/...sc=also_try_p7
I also used the pattern on this website to make some embroidered felt envelopes last year. I may string these across another one of our fireplace mantles, or we might chop down a teeny-tiny sapling from our backyard and make a miniature Christmas tree display to hang the envelopes from. Or ooh, maybe the "thing" can be finding each day's envelope on the tree and moving it to the garland.
http://allsorts.typepad.com/allsorts.../now_what.html
It's not too late, if you want to do something with your little ones! The envelopes can be folded in a couple of hours, tops, and you can look at your town's schedule of community festivities, brainstorm some indoor craft projects, or write down particular books you'll read that day. LOs love the surprise of opening something up and the anticipation of counting the days; they don't need "stuff" inside.
If nothing else, make a paper chain to count down to the holidays.

We've done a multi-holiday one -- inspired by this blog post:
http://dawnathome.typepad.com/by_sun...rchain-wi.html -- incorporating Christmas, our new baby's due date, January crafts, Valentine's Day, and family birthdays. Simply taking off a chain is its own reward at this age!
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