Homework Solutions has a pretty good one - you can cross off what doesn't apply to you but you will at least know what should be in there. Google says you can get it here:
http://info.homeworksolutions.com/nanny-contract-work-agreements

There is one you can buy and customize called the A to Z contract.

I just wrote my own.

Does anyone know where I can get a basic employment contract for a nanny? I'm New to all this stuff.