The simplest activities are the best with kids! Make a spider web out of painter's tape, let them throw scrunched up newspaper ball to see if they can get them to stick.
Halloween game for kids .
Halloween Math Worksheets Free Kids Printable - these were awesome. Good for several ages - colour by number, addition, subtraction, multiplication or division
This wasn't for halloween, but I bet after you pull out all the tees the light show with a candle inside would be awesome!
It's Written on the Wall: 23 Fun Halloween Games, Treats and Ideas for your Halloween Party