In our recent service of prayer at Christ Church, we taught a version of what is called the Jesus Prayer: “Lord Jesus Christ, Son of God, have mercy on me, a sinner.” Other versions would be, “Lord Jesus Christ, Son of God, have mercy on us.” I have been using this prayer for several years now as a form of “praying without ceasing” – repetition that is not of the “vain” or meaningless variety (Mat. 6). (click here to see the transcript of the service.)
N. T. Wright has adapted and expanded this to a Prayer of the Trinity. Here is the article from ntwrightpage.com that gives more background and suggestions for prayer. Check it out!
Also, here is a link to an article that goes into more detail on biblical basis and practice for praying the Jesus Prayer.
Scott McKnight of North Park University has an excellent blog that has tons of great theological discussions and links to many Prayer traditions that we can learn from.