Yesterday (January 16th), our Church celebrates the Veneration and the many miracles which came about through the Precious Chains of the Apostle Peter.
First, here is the account from the Greek Orthodox Archdiocese website (http://www.goarch.org/chapel/saints/388):
"Herod Agrippa, the grandson of Herod the Great and king of the Jews, grew wroth against the Church of Christ, and slew James, the brother of John the Evangelist. Seeing that this pleased the Jews, he took Peter also into custody and locked him up in prison, intending to keep him there until after the feast of the Passover, so that he could win the favour of the people by presenting him to them as a victim. But the Apostle was saved when he was miraculously set free by an Angel (Acts 12:1-19). The chains wherewith the Apostle was bound received from his most sacred body the grace of sanctification and healing, which is bestowed upon the faithful who draw nigh with faith.
Here is the account from the Orthodox Church of America website (http://ocafs.oca.org/FeastSaintsViewer.asp?FSID=100202):
"The Veneration of the Honorable Chains of the Holy and All-Praised Apostle Peter: In about the year 42, on the orders of Herod Agrippa, the Apostle Peter was thrown into prison for preaching about Christ the Savior. In prison he was held secure by two iron chains. During the night before his trial, an angel of the Lord removed these chains from the Apostle Peter and led him out from the prison (Acts 12:1-11).
Christians who learned of the miracle took the chains and kept them as precious keepsakes. For three centuries the chains were kept in Jerusalem, and those afflicted with illness and approached them with faith received healing. Patriarch Juvenal (July 2) presented the chains to Eudokia, wife of the emperor Theodosius the Younger, and she in turn transferred them from Jerusalem to Constantinople in either the year 437 or 439.
Eudokia sent one chain to Rome to her daughter Eudoxia (the wife of Valentinian), who built a church on the Esquiline hill dedicated to the Apostle Peter and placed the chain in it. There were other chains in Rome, with which the Apostle Peter was shackled before his martyrdom under the emperor Nero. These were also placed in the church.
On January 16, the chains of St Peter are brought out for public veneration."
Finally, St. Nikodemos of the Holy Mountain, in his Neon Eklogion, devotes a lengthy section to discussing the miracles associated with the Precious Chains of St. Peter. I'm not sure if a translation exists (perhaps in the Great Synaxaristes), but if not, perhaps at some point this in-depth discussion of the lives and miracles of the Saints can be translated. (For the Greek version, see the Νέον Εκλόγιον: http://anemi.lib.uoc.gr/search/?dtab=m&search_type=simple&search_help=&display_mode=&wf_step=init&show_hidden=0&number=10&keep_number=&cclterm1=%CE%9D%CE%AD%CE%BF%CE%BD&cclterm2=&cclterm3=&cclterm4=&cclterm5=&cclterm6=&cclterm7=&cclterm8=&cclfield1=term&cclfield2=&cclfield3=&cclfield4=&cclfield5=&cclfield6=&cclfield7=&cclfield8=&cclop1=&cclop2=&cclop3=&cclop4=&cclop5=&cclop6=&cclop7=&isp=&search_coll%5Bmetadata%5D=1&&stored_cclquery=&skin=&rss=0&display_mode=detail&ioffset=1&offset=15&number=1&keep_number=10&old_offset=11&search_help=detail)
But roughly, St. Nikodemos discusses that the Chains of St. Peter not only worked healings of physical ailments, but those for the soul, too. Once, a wise and pious Christian came to the Pope of Rome [who was Orthodox before the Great Schism] to confess a grave and fatal sin. The Pope showed joy at the man's repentance and confession, and he gave the man a canon of penance to fully deliver him from his sin by the authority of the Foremost (Κορυφαίον) of the Apostles [St. Peter]. So he told the man to put the Holy Chains of the Apostle on his hands, feet and body, and to proceed around the church where the Holy Apostle's Remains were kept seven times. Then, he would enter the center of the church, and hit his head against the door covering the Remains, and if they would open on their own accord, he would be assured of the forgiveness of his sin. The man did all this, and he touched the container of the Apostle's Remains, beseeching his help. And--O the speedy sympathy of the Foremost of the Apostles of Christ, Peter!--the seals were breached and the locks and doors opened on their own, and the man was assured of Christ's forgiveness! He returned to his home full of joy. For to him who received the keys to the Kingdom of Heaven and opens to whoever he wishes, it is paradoxical to see that the gates of that place [the container of the Apostle's Holy Relics] which were locked by the righteous from the unworthy, opened accordingly to him who was purified by repentance. And that Pope continued in the ways of compassion, and sharing this story with other Christians, he would fill them with joy. He became a model in the giving of canons, and gave confessing Christians a way of entreaty, and in this way they received the forgiveness of their sins.***
[***Note: So that this story is not misinterpreted, here is a short quote about the so-called "kanona" or canon of penance: "It is accompanied by our acceptance of whatever penance or kanona that may be possibly assigned by our spiritual father (e.g., fasting, almsgiving, or whatever else he considers suitable). We also must fully comprehend and accept that such penance does not constitute a “sentence” or a “punishment,” but it is a therapeutic and pedagogical element of our spiritual healing and means by which our spirituality is increased." (taken from: http://members.cox.net/orthodoxheritage/MOM%2005%202006.htm) Thus, Christ Himself runs to embrace us again as soon as we turn back to Him in repentance, and the canon is meant only to further help heal the penitent.]
(taken from: http://www.goarch.org/chapel/saints/388)
St. Peter the Apostle, intercede for us!
Through the prayers of our Holy Fathers, Lord Jesus Christ our God, have mercy on us and save us! Amen!