Laparoscopy
Laparoscopic surgery offers a remarkable reductions in pain for many surgeries including spays, gastropexies, and liver biopsies.  The surgeon performs the surgery using a camera and tools inserted through a dime-sized hole leaving a smaller incision to heal.  It allows for much finer, more precise techniques internally - leading to less bleeding and tissue trauma - and less pain!  Studies have shown up to a 65% reduction in pain for pets whose surgeries were done with laparoscopy versus traditional techniques.

The picture on the left is an internal picture after a laparoscopic spay.  Note the lack of bleeding and tissue trauma - which means much less pain!
 

The picture on the right is an internal picture after a traditional spay.  Note the bleeding and tissue trauma.