Today, the Unitarian Universalist Association has one hymnal with a supplement, and it's halfway or more through its lifespan. There was once a time when Unitarians and Universalists -- and other denominations -- had many hymnals, some with specific uses. For youth groups or camp meetings say. Not a good development, I think.
I found one of these old, topical hymn resources -- more a pamphlet than a hymnal -- at a bookstore in York, Pennsylvania, while Hubby and I were on vacation. Undated and simply titled "Familiar Hymns and Tunes" the booklet seems ideal for a summer chapel, conference or other setting where you want people to be be able to sing without much coaching. The cover didn't scan well -- too dark -- but this copy was from "Universalist Church, Good Luck, N.J." suggesting use at Murray Grove.
To inspire you, I've scanned this hymn resource as PDFs and you may downloadÂ a ZIP archive of it here.