ggplot2 plot without axes, legends, etc

As per my comment in Chase's answer, you can remove a lot of this stuff using element_blank:

dat <- data.frame(x=runif(10),y=runif(10))

p <- ggplot(dat, aes(x=x, y=y)) + 
        geom_point() +
        scale_x_continuous(expand=c(0,0)) + 
        scale_y_continuous(expand=c(0,0))   

p + theme(axis.line=element_blank(),axis.text.x=element_blank(),
          axis.text.y=element_blank(),axis.ticks=element_blank(),
          axis.title.x=element_blank(),
          axis.title.y=element_blank(),legend.position="none",
          panel.background=element_blank(),panel.border=element_blank(),panel.grid.major=element_blank(),
          panel.grid.minor=element_blank(),plot.background=element_blank())

It looks like there's still a small margin around the edge of the resulting .png when I save this. Perhaps someone else knows how to remove even that component.

(Historical note: Since ggplot2 version 0.9.2, opts has been deprecated. Instead use theme() and replace theme_blank() with element_blank().)

Re: changing opts to theme etc (for lazy folks):

theme(axis.line=element_blank(),
      axis.text.x=element_blank(),
      axis.text.y=element_blank(),
      axis.ticks=element_blank(),
      axis.title.x=element_blank(),
      axis.title.y=element_blank(),
      legend.position="none",
      panel.background=element_blank(),
      panel.border=element_blank(),
      panel.grid.major=element_blank(),
      panel.grid.minor=element_blank(),
      plot.background=element_blank())

Current answers are either incomplete or inefficient. Here is (perhaps) the shortest way to achieve the outcome (using theme_void():

data(diamonds) # Data example
ggplot(data = diamonds, mapping = aes(x = clarity)) + geom_bar(aes(fill = cut)) +
      theme_void() + theme(legend.position="none")

The outcome is:

If you are interested in just eliminating the labels, labs(x="", y="") does the trick:

ggplot(data = diamonds, mapping = aes(x = clarity)) + geom_bar(aes(fill = cut)) + 
      labs(x="", y="")

'opts' is deprecated.

in ggplot2 >= 0.9.2 use

p + theme(legend.position = "none")