My officemate and I have a small child in our office...
So far we've given her a typewriter to play with, I've run around pushing her up and down the hallwayin a big printer box, had a treasure hunt, we've hidden in various places around the office, searched for her in various places and are now going to play with paper dolls and experiment with making colours with only a few colours of pens.
We've also done loads of magic tricks, which were loads of fun - just basics like working out which cup the liquid paper's hiding under, etc. But fun :)
Small children are not too bad once they've gotten over the shy thing. This one belongs to a workmate who's brought her along for the day. The hide and seek was pretty fun, actually, now that I think about it :) Haven't done that in years.
Still, glad that I got the major important work for the day out of the way in the morning!
Small child's quote of the day:
"I bet sometimes you don't get much work done."