Many websites and magazines compile "best places to work" lists. Many of the lists are compiled by reviews of employer-submitted practices and policies, but others are compiled from other types of submissions. The lists usually contain a brief description of the practices that make the company an "employer of choice."
These web sites are intended for prospective applicants. Much of the information comes from anonymous employees who visit the pages. Remember, though, that the best insiders are people you know! It is crucial that you develop and maintain networks of people in your field.