Husband likes to have his back scratched during sex. It's not something I do often because hard scratching with my nails really bothers me for some reason. It gives me a very uncomfortable feeling. Sometimes I just get so caught up in the moment that I just dig my nails into his skin and he loves it.
While I don't enjoy being scratched hard, I do love to be scratched lightly during sensation play. We have lots of different toys to do that with. I think my favorite toy is a set of meat shredder claws. I would love to get more toys for this purpose.