Summertime by Janis Joplin is in Em at 90 beats per minute and runs 2:16 across 18 bars. It uses 15 chords — Em, C, B7, D, G, Am, Am7, C#m7, and a few more. The chord diagram changes as the song plays and the words light up as they are sung, so you can strum and sing along without reading ahead.
Want the melody line note by note? Summertime guitar melody tab.