I was looking into this earlier to try fixing a display that was being offset on an old tv screen. The display was going off the left side of the TV, causing a black bar on the right side.
I was trying xrandr, and fixed it somewhat by offsetting the display back, but somehow it did not fix the right side - it seemed as if the display had went under the black bar.
But yeah you can offset, stretch, skew and rotate with xrandr