What are the best jobs for people who don't like/get along well with people?

I have a friend, well she likes me, but not many other people, and hates working with others (says it stresses her out, I believe her) prefers to work alone, but can't think of what kind of job to go for that is a more solitary profession...we were brainstorming new career paths for her...any ideas? She has a B.A. and is willing to get more training in something if need be but It has to be paid work.