The Baggler - Bag Carrier
Although the name of this product is slightly reminiscent of "the Burglar" (as in Mickey D's Hamburglar), it's still a great product. I know I get tired of heavy plastic grocery bags cutting into my fingers when I'm carrying them up 3 flights of stairs. The Baggler has a comfortable ergonomic handle that allows you to carry many things conveniently and painlessly.
When I go to the mall, I usually walk out with a ton of stuff and it KILLS my fingers, having those little plastic sacks wrapped so tightly around them. So this product definitely looks like it would work for me. You could even use it at the grocery store.