K.V.
They have them that look like stuff animals (the one I seen was a bear). Google nanny cams and A BUNCH will come up.
I had problems with one of my sitters, and looked into getting one. But I couldn't afford it. I ended up firing the babysitter anyways, because my daughter wasn't happy, she got caught in quite a bit of lies, she had friends/boys over when I told her not too, and she did things in my house I didn't approve of.
I am still looking into getting one. Hopefully when my $$$ situation is a little better.