Someone has created a fascinating visual depiction of the changes in the language of pop music since 1960 by graphing the occurrence of various words in the Billboard Top 100 songs from 1960 until the present. It's a slide show, including twenty or so words. Each rectangle represents a song, and darker colors represent greater frequency of the word in question. "Baby," shown below, seems to have remained fairly constant. But I think you'll find some very interesting and significant differences in others; interesting, but mostly not surprising to me. Click here to view the entire sequence.