The Mennonite church has a tradition of a capella singing. This is changing in some areas but most congregations will have at least one or two a capella songs each Sunday. The piano, organ, guitar, or other types of music are played prior to the service, during the offering, etc.
In 1992 a new hymnal was co-published by the Mennonite Church and the Church of the Brethren. There are many new as well as old hymns. The book is called, Hymnal: A Worship Book and is available online from Herald Press .