I got the sign off ebay as well:
Bowser pinata (also from ebay). I thought the kids would like giving Bowser a good whack:
For an activity, we made up an obstacle course in the backyard. The kids with the fastest time won a prize (we did an over and under 5 set):
Each kid got a Mario hat and mustache. I made the hats from foam and I bought the mustaches from amazon.com:
We also had a Yoshi egg hunt that I forgot to take pictures of. I bought some white easter eggs (and mixed in a few colored ones too) from amazon.com and then got a green paint pen and drew spots on them. Then I filled them with candy. In a few, I put a gold star, which meant that you won and extra prize (mushroom keychains I bought off of ebay). I also hid a mini-Goomba in the yard (also from ebay) and whoever found it won a prize too.