Technically, this doesn’t have anything to do specifically with Christian music, but USA Today did a great story on Christian abolitionists involved in helping sex slaves regain their freedom.
It connects to Christian music, though, because so many artists are actively involved in promoting social justice, and are involved in abolitionist movements. Sara Groves, Derek Webb, and The Wrecking are three names that come to mind right away.

The article mentions Justin Dillon, onetime front man for the popular Christian rock band Dime Store Prophets. Dillion released an anti-trafficking documentary last fall, Call + Response. I haven’t seen it, but it’s just one example of how musicians are combining their art with their passion to come to the aid of those in need.
It’s what Jesus commands, and what God talks about repeatedly in the Bible. Justice, mercy, compassion, pursuing those is our act of worship.
I recommend checking out the article, and also supporting those artists involved in social justice causes – not for the publicity, but because Christ commands them to.
What songs topped the Christian music charts for 2008? Check out this Gospel Soundcheck post, Radio and Record’s Most Played Christian Songs of 2008.