My puppy used to do this. Infact almost every puppy you meet will do this at some stage XD (Especially when they're teething!).

And used to pull a really high pitch "OW!" which would distract her because she thought she really was hurting me. Other than that, I used to give her toys as a replacement for my hands lol, though occassionally she'd lean over from the toy to nip me too.

When she used to get really nippy to the point she was actually hurting then I'd tell her NO! and it would startle her a bit into getting down. Then I'd normally make her sit or work for a few titbits to take her mind off nipping.

It took a few weeks to sort out our puppies nipping but we got there in the end.

Stacey xxx