require(rCharts)
n1 <- nPlot(mpg ~ wt, data = mtcars, type = 'scatterChart', group = 'gear')
n1$chart(tooltipContent= "#! function(key, x, y, e){
  return '<b>Disp:</b> ' + e.point.disp + '<br/>' +
    '<b>Cyl: </b>' + e.point.cyl
} !#")
n1