Kakooma Halloween Tournament. It's scary how much fun kids can have playing math. Join thousands of thousands of students and hundreds of teachers competing for prizes such as a Kindle fire HD by signing up at GregTangMath.com/kakooma. Oh, I almost forgot to mention. It's completely free.
Probability and Patterns with Pascal...this would be cool for an upcoming math module. The students could fill in the rest of Pascal's Triangle and then write a report about the history and patterns found.
Show me the MONEY! For this foldable, you have to cut each flap. In first grade I always prepared the books ahead of time, but I think 2nd graders could definitely handle making them on their own. On the inside, the students describe the coins and write how to make a dollar using the coins on the flap. It is great for coin recognition as well as counting money.