I work part-time at the local library. It's really quiet and peaceful, to me at least. The only interaction I ever really do is help customers locate certain sections and books. Other than that, it's a pretty laid back job. I just basically sort books, input data on the computer, and help people locate things as I mentioned before. I'm getting $7.25 an hour since it's only part time, but my manager told me that she'll pay me $13 an hour if I do full-time. Not a bad deal, especially for such a menial job.
Other jobs that might suit a shy person are freelance writing or photography, which is where I'm aspiring to land a job in the future. Also, one of my good friends who has SA got a job as a Search Engine Evaluator. She gets to work from home and make her own hours which is awesome. I think finding a job where you can work from home is one of the best options.