I've been volunteering at a hospice for the past year, and it has been an EXTREMELY good experience. The nurses usually tell me which patients are cranky and which aren't lucid, so I tend to mostly just visit those who enjoy conversation. Unlike many other volunteering activities, especially those in a hospital, you actually get real patient-interactions.
I remember the first time I visited a patient. It was some old guy lying in his bed, and as soon as I walked in, he started whispering/yelling in a raspy voice about how he's dying and how he's gonna die. I kinda just froze there, not sure what to do or what to say. But after speaking with many patients, you sort of get used to all types of patients and you understand how to speak with them. Some of them have awesome experiences to share, and some of them just need to be comforted. Sometimes there are no patients who can/will talk to you, then I just either chat with the nurses or help them with chores. It has been an amazing experience, I would recommend it to any premed.
Beware though, of possibly a long training period. At the place I volunteered, you had to send in your application, they'll do a background check, then attend an orientation, two 7-hour training sessions, an interview, and another orientation before you may start visiting patients.
Also, there's the problem of becoming attached to some of the patients, because in a hospice, obviously, many patients do pass before long. It can be sad, definitely, but I think it's still rewarding because you know that you did make a difference, no matter how small, during their last days.