It was also apparently a pioneer in the practice of using microphones in theatres. The orchestra pit included several saxophones, and Horne, who never had a particularly big voice, couldn't be heard over the multiple saxes. So she was given a body mike to allow her to be heard without reducing the orchestration. (It wasn't the first body mike, though: Mary Martin used a mike in Peter Pan so she could be heard clearly when she was flying around the stage. It was, most likely, the first time amplification was used to allow the singer to be heard over the orchestra while standing still.)
Anyway, the best song in Jamaica is "I Don't Think I'll End It All Today," one of my favorite songs ever: Arlen's insanely catchy tune combined with Yip Harburg's just-plain-insane lyric -- a grotesque catalogue of violent death that nonetheless carries an upbeat and optimistic message -- makes for the most unique "charm song" ever written. And it's a reminder of the biggest reason why Harburg is my favorite lyricist: his insistent on using specific, tangible images instead of vague ones. Not only is he specific about methods of death that the singers won't use, but he's specific about the reasons why life is worth living. It's a lyric with lots and lots of nouns and verbs, few adjectives.
Here it is, from the original Broadway cast led by Horne and Montalban and conducted by Lehman Engel: