He started out in the 1970s with a group of friends playing "Jawaiican" music--a hybrid of traditional Hawaiian folk songs with reggae. From the short monologues on his records, and his nickname ("Brudda Iz"), you immediately sense the connection of the two subcultures.
Kamakawiwo'ole's disarming medley of "Somewhere Over the Rainbow/What a Wonderful World" was included on the iTunes Music Store's album of Essential Covers, and quickly became one of the top 10 downloads on the Apple site. (You might recognize the track, from his Facing Future album, from the movie Meet Joe Black or from the 2001 season finale of "E.R.")
"Somewhere Over the Rainbow/What a Wonderful World" reached #4 on the iTunes Top 100 Downloads today. That means a Hawaiian singer/ukelele player--who died in 1997--is brushing aside the latest singles by Britney Spears and Justin Timberlake and challenging OutKast, No Doubt, and Norah Jones. How did this happen?
Give a listen; there are four of his albums in the iTunes store. I recommend the operatic track "Hawai'I '78."