a lot of people including me were very involved in volunteering in the Free Clinic, we loved it, the shifts were highly sought after
it was low key, low stress, as you could sign up for whatever shift you wanted
it offered amazing first hand clinical experience, and there was lots of time for great teaching from dedicated residents and faculty, lots of time with patients honing skills
in hindsight, it was frankly better than most of my 3rd and 4th year rotations, and did a lot to prepare us for them
however, I imagine it varies greatly institution to institution