set.seed(1)
dat <- data.frame( xx=sample(10,9),
                   yy=sample(20,9),
                   group=c('A','B', 'C')  )

ggplot(dat, aes(x=group, y=yy, fill=group)) + geom_boxplot()
ggplot(dat, aes(x=group, y=xx, fill=group)) + geom_boxplot() + coord_flip()

datPlot <- melt(dat)
ggplot(datPlot, aes(x=group, y=value, fill=variable)) + geom_boxplot()