For my mom, some of her best gifts were clothes - not because she loves getting new clothes, but because she had lost so much weight that she only had 3 outfits that fit her. The new tops or bottoms broke up the monotony a bit - especially when she was wearing the same things over and over again to treatments. The other thing that really helped was that friends with dogs would bring over their dogs when they came to visit. If your friend is a dog lover, I highly recommend it. My mom's face never looked happier than when our new neighbors came over with their puppy. I wish I had been able to take a picture.
Overall, anything helps. And, for those taking care of yoru friend, a pot of food is a huge help. I cannot tell you how many times my husband and I either did not eat dinner or wound up eating at 10pm after trying to get my mom settled for the night. A neighbor brought down a pot of chicken soup and some chicken stew one night and we felt like the luckiest people around.