Many probably know this already but I thought it was worth posting for those of us with kids ( especially younger ones )
There's been quite a lot of publicity with kids running up bills from In App purchases on games and having had this happen only this week I though it worth posting that you can actually disable In App purchases through the device. Apple were good sorting it out for us although it was only £27.99.

Go into Settings, then General and click on Restrictions.
From here you click Enable Restrictions at the top ( at this point you may have to enter or even set up a 4 digit PIN code )
This then allows you to enable restrictions , the In App Purchases one is half way down.