There are some really cool Crayola items that you can get from any toy/drug store.  There are these markers that you can draw with on black paper, and it comes out florescent... it's really cool.  They can draw with these, which will entertain them for a while, and will also create some fun things to hang up.  You could also draw things on strips of paper and make chains with the paper... then hang the chain from the roof.  That's always fun.