Any ideas for a part-time job for a full-time professional?

Does anyone have any ideas for a part-time job for a professional that works full-time in marketing? I prefer a job that has less interaction with people and I can only work a maximum of 15 hours a week. I don't want to do waitressing or anything at a bar. I was thinking of maybe working at a book store or a large retailer, but am open to other ideas.