Below are 2 processes of the same RAW file. The first was done in Lightroom 4.2, the second in RawTherapee - latest version. I'm posting them to show the neat little trick that RawTherapee can do.
It has 3 "tools" to correct "Horizontal Perspective", "Verticle Perspective" and a "Lens Correction Profile". The "Horizontal Perspective" tool works as if you have a vertical bar through your image and can swivel the image left or right around the bar. The "Vertical Perspective" tool works as if you have a horizontal bar through your image and can tilt the image up or down. I haven't displayed use of the "Lens Correction Profile" but it corrects - and straightens - horizontal and vertical distortions - e.g. can make rounded picture frames straight.
Interestingly, the image was taken with a single 100 watt bulb to my right. The RawTherapee correction has adjusted the light as well!
First image - Lightroom.
Second image - RawTherapee. Using "Horizontal Perspective" correction.
I repeat - both these Jpegs were developed from the same RAW image. C&C welcome!