When my DH was in the nursing home for 3 years, I used to pick up "Reminisce" type magazines and donate them. They were read and passed around, and I could always hear someone saying "I remember that. I used to have one of those. I used to do that". They love to remember their past.
Hats, gloves and fancy handbags and such for dress up tea parties.
One of DH's nieces and her own DH used to come in weekly with another couple and play country music. Another lady who was an excellent musician would come in now and then and play classical music on the piano they had there. Other groups, from children to adults would come in now and then and sing, Anything that broke up the boredom was welcomed.
Donations of baby sized dolls for some of the ones who want something to hold. Soft large teddy bears to hold, men included.
CDs of recent AND old movies, you could check to see if they already have them.
Coloring books...it hit me hard to see my Dh, earnestly coloring in childrens' books, intent on staying in the lines. Crayons too.
Someone to bring in a dog or cat for them to pet. I got permission to take in my cat for DH to pet, and suddenly discovered that he was surrounded by others who wanted to touch the cat. Koko made DH feel good as he laid on DH's chest and purred as others rubbed his back.
Clothes, in good condition. Some of these folks have no kin left at all, and have lost all of their own personal possessions. Soft shoes, thick socks (old feet are usually cold) and clothes that are easy to put on and remove. Some men have grown up wearing those feed store billed caps, and don't feel comfortable without them.
Thank you for taking the time to do something for people most others have forgotten.
If you need something for them that can't be provided by the place itself, why not try some of the service clubs closest to you? Or even FreeCycle?