For stay at home working moms, how do you keep your toddlers busy while you work and no one is available to look after them?

I put him in a large box and give him crayons. I also make him do shuttle runs and "compete" with the dog. If your kid loves looking at photos of themselves you can also print albums and get him/her to find all the pictures of himself (or grandparents or whoever) and get him to tell you stories of the event. Books and busy boards work well too. If I'm desperate and work is urgent then TV it is but I limit to an hour.