My 99 V70 has wicked bad camber problems. I thought i would post a pic of my tire.
I have ordered new heavy duty springs from IPD, all the bushings look OK. never been in an accident. This tire is the passenger side, the drivers side was worse but I already replaced it.

Image URL
http://www.brickboard.com/IMAGELIB/volvopic.htm?js_link=1&id=11286

THAT appears to be more than just a little weight in the rear. Check the suspension bushings and see if they still exist! Your shocks are also gone as the worn spots indicate on the tire.

I suspect that jacking the wheel off the ground will show the shock bushings have left the car, and the upper shock mounts are probably dust.

EDIT: Are the insides of the tire rubbing anything when the car is loaded?
Look for shiney spots.

The shocks are 3 Yrs old. Did them myself. I will check the mounts. I dont see obvious bushing damage. I did notice, when jacking, as the wheel is lifting off the ground, a clunk and a shift in the wheel. I cant figure out what it is. I have assumed that it is the spring seat. I will look more closely.

The wheel should slide inwards just slightly as the jack removes the weight and the body of the car moves towards the other side. But no CLUNK.

Did you take a good lock at the torsion arms, rubber bushings?

The shocks being only 3 yrs old is a good thing, you can probably rule them out?

After much detective work, the noise that I am hearing is a broken trailing arm bushing. now i need instructions for replacing.

Photo at
http://www.brickboard.com/IMAGELIB/volvopic.htm?js_link=1&id=11287

The part is this
http://www.fcpeuro.com/products/volvo-trailing-arm-bushing-kit-rear-right-3516496

THAT will screw up the camber very nicely!!! It is not an easy replacement, there are write ups on Volvospeed and Matthewsvolvo.

Replaced broken anchor bushing, installed new IPD heavy duty springs. Car rides like dream.

How much weight are you carrying? Do you leave the car loaded overnight?

As a crude test, you could put a level on the outside of each wheel unloaded, then loaded.

Ask the seller of the heavy duty springs what you new load rating would be.

Your car is not a pick-up. In fact, I think that it is heavy in the rear to begin with.

You could try Nivomats.

When I picked up a B16 with tranny, my '96 855R dropped 3 inches, it was level within 1/4 mile.

I do carry some weight, camera and lighting equipment. And I often leave it loaded overnight. I am afraid I do treat it a bit like a pick-up truck.
I try to put the heavy stuff right behind the front seats, and leave the back end a little empty.