This is a simple idea for 'unfinished worship' - getting people to interact and participate in the leading of worship in a safe, pressure-free way. Ask people to open their Bibles at the Psalms, then sing a simple, celebratory song. After you've sung it for a few minutes, invite people to read a verse or two from the Psalms that jumps out to them. You can keep the music or rhythm going on underneath, but make sure people can be heard.
In a bigger group you might need to pass a radio mic around, but if you can avoid that all the better. We've used this lots of times now, and it helps people who would never pray outloud to speak out, lead and shape the congregation's praise. You can close the activity by singing the song again.