Most stores are taking part in the after-Christmas sales. Here is a list I have compiled of some of my finds.
Walmart stores - 75% off most Christmas related items (giftsets, decor, candy, food items, paper products, etc)
Target stores -70% off original price (slim pickings left at most stores - bows/giftwrap/decorations) and their has been little confirmation on if we will see it go to 90% this year.
Walgreens and CVS - 75% off Christmas related items
Kroger - I have noticed a lot of toys have been marked down 50% off at Kroger (ex : Cars 2 small vehicles are $1.99 each versus $3.99)
January is also the time that Target has their annual 70-75% off toy sale - it is speculated that this sale will take place in the next two weeks!