"No Woman, No Cry (Live)" (Bob Marley & The Wailers)

Even if you're not the biggest reggae fan, chances are you know the song "No Woman, No Cry"—specifically the version that was recorded live at London's Lyceum Theatre in 1975, which appears on Bob Marley's 1984 hits collection, Legend.  It's a song that transcends genre.  The musicianship, the crowd participation, and Marley's soulful performance elevate the song to anthemic proportions.  And as if one memorable hook weren't enough, the song has two memorable hooks: the reassuring No woman, no cry, and the rallying Everything's gonna be alright!  
It's impossible not to feel rejuvenated after hearing this song.
Although there are a lot of (odd) interpretations of "No Woman, No Cry" out there on the Web, I think the most plausible is that it's a political song about pre- and post-independence Jamaica and the perils faced by the poor.  In the lyrics, Marley not only discusses the abject poverty and unrest in Kingston's Trenchtown slum, but he also paints a picture of the profound hope and sense of community among its citizens, reminiscing about his own upbringing in the neighborhood.  In fact, my take is that he's not singing to any one woman in particular; he's addressing Jamaica, telling her that everything will turn out okay in the end.
A little extra factoid: if you scan the liner notes of Legend, you'll notice that the track is credited to "V. Ford."  It always puzzled me a bit, considering there was never a "V. Ford" in The Wailers.  
It seems that Marley wrote the song himself but gave credit to an old friend of his, Vincent Ford, who ran a soup kitchen in Trenchtown.  Ford had befriended and supported Marley before his rise to fame, so as a "thank you," Marley made sure Ford and his soup kitchen got the royalty checks for the song.