During the last few years of prosperity, stores had largely stopped doing this, so I don't think I've posted much on this before. Forgive me if it's a repeat.
Lately (since the economy crashed), the stores have started going back to their old habits of marking down holiday items the day or two after the holidays. Walmart held on to their Christmas stuff until now, but today the WalMart here in Longmont started marking stuff down. Really down. Candy was 50% off (not enough to entice me), but everything else Christmas-related was 75% off. In other words, you could get $100 worth of Christmas stuff for next year for $25. Red cups were 16 for a dollar. Stockings were $.25. Christmas decorations were for pennies. I got icicle lights for $1.75 a box, and a string of 400 tree lights for $1.75. Wrapping paper rolls were $.25. That's just a sampler. King Soopers, a local grocery store, also had things marked down about 75%--so I got all kinds of baking things (cookie cutters, Andes Mint Chips, cherry chocolate chips) for less than $.75 a piece. I also found small toys there marked down to $.50, so I got Nathanael's birthday presents.
WalMart's toys were also 50% off, so you could conceivably buy all of next year's birthdays and Christmas (if you MUST buy new, which I've already said is not the wisest move for penny pinchers) for half what you'll spend later, if you have a place to store stuff.
There are two things you can do with this kind of sale. You can stock up for next year (buy all the stockings, Christmas lights, decorations, next year's tree--for $10 instead of $40) and store the stuff. Since most of us store Christmas things anyway, this is a great time to prepare for next year, replace things that broke over this year's holiday season (worn strings of lights, glass ornaments, etc). At the very least, get a couple of boxes of ornament hooks for a quarter each and throw them in with your ornaments as you put them away.
The other thing you can do is buy things you use on a regular basis and either ignore the Christmas motifs or buy red or green or gold things that aren't specifically Christmas-themed (just colored) and use those. For example, I found cereal bowls for $.17 each. I bought blue ones with snowflakes on them, which we will put into our regular dish rotation along with the plain red cups and santa-print red cups (since I don't care if they have Santa on them as long as they don't break when the kids drop them and are cheap enough that if they use them and lose them outside, it doesn't matter). I also found gold-colored fabric place mats for a few cents a piece. There were also red and green brocade. All of these are usable in regular company all year, but had Christmas-themed LABELS, so they had to be marked down, too. (I might not put red and green on the table at once in May, since that will look Christmassy, but all red? It goes with my kitchen!). Likewise, while some wrapping paper is definitely Christmas-themed, some is just plain red, green, or pale blue and can be used throughout the year for wrapping presents and for crafts, especially for your own small children's birthdays (since they just want to eat it anyway!).
This is also a great time to stock up on craft supplies--various kinds of ribbons, trims, papers, etc. are really cheap and can be added to your stash.
Shopping the markdowns after Christmas is a really valuable thing for penny pinchers because you end up getting things you will otherwise have to buy later in the year for 3 times more. It makes a lot of sense to spend $100 now and get $400 worth of stuff that you're going to use. Stuff you buy every year (you know you do).
You can also shop markdowns after Easter, Valentine's Day, and Halloween, but what you mostly get on those holidays is Candy. If you haven't trained your kids to care, you can get marked down Christmas candy to give your kids on Valentines' Day, Valentine Candy for Easter, and Easter (and, increasingly, 4th of July) stuff for Halloween. Easter is the only one that is like Christmas in that there are necessary supplies that you end up buying every year that you can stock up on (easter grass, easter baskets, and easter egg dye all last really well. Actually, if you put them in a sealed container, a lot of the non-chocolate easter candy lasts, too!).