JJ is one of the better musicians out there..........Ben kweller is along the same lines but more folk/rock but just as good.
Jack Johnson is a boss. If you like him you'll probably enjoy Donavon Frankenreiter. (JJ and Donavon actually play a lot of songs together.) Also check out the band, "Animal Liberation Orchestra". Specifically the song, "Girl, I Wanna Lay You Down". Pretty much same exact feel as Jack Johnson, primarily because he plays with these guys occasionally Could go on for hours!
[ame=http://www.youtube.com/watch?v=OyCaiaeRAWo]Miles Davis - A Tribute To Jack Johnson (1971) Full Album - YouTube[/ame]