If your loved one is a person of faith, consider bringing spiritual practices to him or her. Even if he or she isn't able to show much responsiveness, studies show that there's probably still a level of perception, and spiritual interactions can be deeply reassuring and relaxing.
Ask clergy to make a house call. Many will, especially when someone has a terminal illness.
Play or sing familiar hymns.
Read aloud from a Bible, book of prayers, or other book of faith.
Hold makeshift bedside services.
Many people find spiritual solace in the outdoors, so you can also bring the outside in with plants, flowers, and a bird feeder hung outside the window -- introducing sounds and scents that bring solace.