I recently wanted to create a ggplot that I could then 'tweak' furthur. This is my solution, to create an .svg file which can be loaded into a suitable application (I prefer Inkscape) and furthur edited / tweaked.

# Build an example Plot
library(ggplot2)
dataframe <- data.frame(fac = factor(c(1:4)), data1 = rnorm(400, 100, sd = 15))
dataframe$data2 <- dataframe$data1 * c(0.25, 0.5, 0.75, 1)

testplot <- qplot(x = fac, y = data2, data = dataframe, colour = fac, geom = c("boxplot", 
    "jitter"))
testplot

# Produce a PNG plot
library(Cairo)
Cairo(800, 800, file = "testplot12200.png", type = "png", bg = "transparent", 
    pointsize = 12, units = "px", dpi = 200)
testplot
dev.off()

#Produce an svg file
library(Cairo)
Cairo(800,800,file="cairo_2.svg",type="svg",bg="transparent",pointsize=12, units="in",dpi=400, width=20, height=20)
testplot
dev.off()