Today is the feast of a saint who has one of the coolest names in history: Pietro Damiani. It just rolls off the tongue like a party.
Peter Damian (1007-1072) is a Doctor of the Church; he was a well-known instance of a tell-it-like-it-is monk (Benedictine), who spent a great deal of his life attacking abuses (particularly simony and sexual abuses) in the church. His most famous work in this regard was the no-holds-barred Liber Gomorrhianus, which earned him the enmity of more than a few people (and a protest letter from the pope, Leo IX, who liked Damian but thought he went a bit overboard). He was eventually made a cardinal; but the pope of the time, Stephen X, had to threaten him with excommunication to get him to accept it. Every time a new pope came to power he would plead -- or sometimes demand, since he was that sort of person -- to be released from the responsibilities of being a cardinal; but his request was steadfastly refused. He played a major role in the schisms of the time. He is often referred to as the Doctor of Reform and Renewal. He is a terribly stern and severe but occasonally very likable figure in history; a very emblem of the fire of moral purification.
One of his more important and influential works is the treatise De divina omnipotentia. Paul Vincent Spade has translated and placed online selections from that work (PDF). You can also find online a letter from Peter on simony. The Medieval Sourcebook has a small selection from the Liber Gomorrhianus. Also available online is a selection from Peter's Life of St. Romuald of Ravenna
