10. Big Brother and the Holding Company - 'Summertime'
Most people who picked up Big Brother and the Holding Company's 1968 LP Cheap Thrills in the summer of 1968 probably weren't huge fans of George Gershwin, but they surely loved Janis Joplin's rendition of his 1935 classic "Summertime." The song first appeared in the opera Porgy and Bess and it quickly became a jazz standard, covered by Billie Holiday, Louis Armstrong and many others. A wonderful showcase for Joplin's vocals, the song was a highlight of her Woodstock set.