Does anyone know of any a cappella works by Bach or any Rennaisance/Baroque German composers for between 2 and 4 voices in any combination?

I'm doing the Bach tour with my Choir this summr, and would like to prepare a little extra music to sing with friends. I did a similar thing on an italian tour a few years ago. Put together a quartet of friends and brought along a few motets and just sang in front of churches or wherever we could. Great fun. I'm having trouble finding anything that would be good for this trip. Thanks in advance for any help!