On the Internet I found the following information on the now defunct spiritweb:
"In the world of Jewish mystics, came to hold the rank of the highest of the angels despite his not being mentioned in the Scriptures. The meaning of his name has never been satisfactorily explained although one interpretation of it is "one who occupies the throne next to the Divine throne." It could also be derived from the Latin 'metator', a guide or measurer.
In a number of traditional sources, Metatron is said to have been the prophet Enoch, who was taken up to Heaven and transformed into an angel of fire, with thirty-six pairs of wings, to continue his days as a celestial scribe. Metatron has also been id entified as the Liberating Angel and the one who wrestled with Jacob; the one who stayed Abraham's hand from sacrificing his son Isaac; and the one who led the Hebrews through the forty years in the wilderness. In certain schools of mysticism, Metatron, said to be the tallest of all the heavenlybeings, became known as Lesser YHWH. In Hebrew, the letters 'LHWH' stand for the most sacred and unpronounceable name of God.
As God has many names, so, too, Metatron was thought to have many names, the use of which was believed to offer the user protection and access to this great angel's powers. Yahoel, Yofiel, Surya, and Lad are just a few of his other names."
(From: Ask Your Angels, by Alma Daniel, Timothy Wyllie, and Andrew Ramer)
"Sitting beside God, Metatron, the throne angel with 72 names, records Israel's good and bad deeds. One mystic said Metatron carries Jewish prayers up through 900 heavens to God." (From: Do You Have A Guardian Angel? by John Ronner)
Some sources also refer to Metatron as an ascended master.