Every year, Working Mother magazine announces its much-anticipated "100 Best Companies." Employers leap to publicize their inclusion on the list, and it's routinely a best-selling issue. But is the "100 Best" -- and similar lists published by other magazines and organizations -- much more than public relations? Large companies are already required by the Family and Medical Leave Act to provide 12 weeks of unpaid leave. In addition to meeting federal requirements, most businesses make the list with low- or no-cost policies and perks such as flex time, child-care resource directories, lactation rooms, and additional unpaid leave. Benefits such as paid family leave or free or reduced-cost child care are much rarer. Most such "best employers" lists are compiled using self-reported data. While Working Mother says the information is fact checked, most companies do not make public the information the magazine says it examines, so there is no way to independently verify it. The magazine...