My cat Maya Linn has been doing that. I'll be sitting at my computer online and BANG!!! she jumps up on my shoulder and purrs and wants some loving. She doesn't do it with anyone else, just me. I don't mind. But I guess when they start doing it with other people and it hurts, that's an entirely different story.

I think the main thing to do is put her down immediately,say no sternly and walk away. She'll get the idea.