"Snow Many Words" is great center activity that can be differentiated for students ranging from levels A-D in guided reading. It can be used in a variety of ways. I find it works best to print this on blue construction paper and allow students to paint the words white, color them with a white crayon, or pick cotton balls apart to fill in the words.
Sticking with the winter theme, there is also a great homework activity for after winter break. Often students forget sight words without continual practice. This homework allows you to write specific sight words that have been "lost" inside the brain clipart, informing parents of what words should be practiced at home!