I found an incredibly cute, fun, easy, and FREE activity for The Crazies on one of my favorite blogs. We tried it last night, and I am not exaggerating when I report that it kept Goofball and Sweetpea occupied for over 2 hours (with a dinner break in there somewhere).
Just gather some waterproof toys from around the house. Place in a large bowl. Fill with water and freeze overnight. Give some appropriate "tools" for excavating the treasures, and let them go to work!