August is the month of the Transfiguration. CanticaNova has a list of music appropriate for the feast itself, and some of the selections are broad enough to be used anytime during the month. Music directors might wish to employ one of these hymns sometime this month.
I would also like to suggest something in the way of organ music, a work which I always play on this feast: Apparition de l'Eglise Eternelle by Olivier Messiaen. It is one of his more accessible pieces and not technically difficult, though it does certainly require a good bit of musical maturity. Its meterless pulse and lack of tonality--while still being harmonically organized--give it some sense of continuity with chant. It is a fantastic work, one that is always well-received, in my experience. Organists might wish to play it sometime this month.