As a somewhat recent organ aficionado/player, I have discovered the ubiquitous genre of organ “trumpet tunes”. These are organ pieces that have a melody which is soloed out on a loud “trumpet” stop (which often go by various names – such as Festival Trumpet, Tuba Mirabilis, Trumpete en Chamade, etc.).
Prior to my organ playing, I knew of the standard trumpet tunes by Stanley, Clarke, Purcell among others that were always played on actual trumpets. When I started playing weddings, though, I found that I didn’t have a trumpet player, but my organ had an organ stop. It is easy to find these standard tunes written in organ only arrangements.
If you’re an organist looking for good postlude pieces, these organ trumpet tunes are very versatile and there is such a wealth of them that it would be easy to play a new one every Sunday service- if not for the likelihood of tiring out the congregation on one type of piece. Many are based on hymn tunes and are written as simple voluntaries for service music. The shorter ones can be used as hymn introductions or even as regular stanza accompaniments, provided they are written to follow the hymn metrically.
These organ trumpet tunes also allow for a simple change of pace if you happen to actually have a trumpeter on hand. As the organist, you can simply omit the solo line and let the trumpeter play it. Congregations always appreciate a thoughtful change of pace from week to week, no matter how small it is.
I suggest looking up some of the organ music of Michael Burkhardt, Michael Helman, or David Johnson for starters. Here is David Johnson’s popular Trumpet Tune in D: