Here's a way to do something good for yourself and others at the same time: Buy your reading material at this spacious yet quietly cozy used bookshop, sporting 45,000 books and records to browse. It's part of Housing Works, a not-for-profit organization that provides housing, services, and advocacy for homeless people living with HIV and AIDS. The collection is terrific and well organized, with lots of well-priced paperbacks, hardbacks, advance copies, and coffee-table books. There's a comfortable cafe in back that serves coffee and tea as well as freshly prepared sandwiches, sweets, and other light bites, plus beer and wine. The bookstore often hosts readings by well-known writers as well as occasional music performances on Wednesday and Thursday evenings; call or check the website for the current calendar.