Guardian Angels

Section 336 of the Catholic Church's Catechism, states: From its beginning until death, human life is surrounded by their watchful care and intercession. Beside each believer stands an angel as protector and shepherd leading him to life. Already here on earth the Christian life shares by faith in the blessed company of angels and men united in God.
Okay, that sounds reasonable and might not be in conflict with the Bible, depending on how you interpret that last line. However did you know Catholics endorse specific prayers directed towards an individual person's personal guardian angel?