It's also the day when Mary (sister of Martha and Lazarus, and therefore not necessarily a "fallen woman") washed Jesus' feet with her tears, dried them with her hair, and anointed them with precious ointment.
Here's the link for the music sung by a man and a woman
http://www.youtube.com/watch?v=K24uYcbLA_U using tone 8
http://www.youtube.com/watch?v=DHIqvNngR2c using tone 4
Here's the link for the sheet music for the second youtube link
Here's the extract from Wikipedia
In the Orthodox Church, the theme of Holy and Great Wednesday is the commemoration of the sinful woman who anointed Jesus before his Crucifixion and Burial; a second theme is the agreement to betray Jesus made by Judas Iscariot.
The day begins with the celebration of the Presanctified Liturgy on Tuesday afternoon. Later that evening, the Orthros (Matins) follows the special Holy Week format known as the Bridegroom Prayer. Towards the end of Orthros, the Hymn of Kassiani is sung. The hymn, (written in the 9th century by Kassia) tells of the woman who washed Christ's feet in the house of Simon the Pharisee. (Luke 7:36-50) Much of the hymn is written from the perspective of the sinful woman:
- O Lord, the woman who had fallen into many sins, sensing Your Divinity, takes upon herself the duty of a myrrh-bearer. With lamentations she brings you myrrh in anticipation of your entombment. "Woe to me!" she cries, "for me night has become a frenzy of licentiousness, a dark and moonless love of sin. Receive the fountain of my tears, O You who gather into clouds the waters of the sea. Incline unto me, unto the sighings of my heart, O You who bowed the heavens by your ineffable condescension. I will wash your immaculate feet with kisses and dry them again with the tresses of my hair; those very feet at whose sound Eve hid herself in fear when she heard You walking in Paradise in the twilight of the day. As for the multitude of my sins and the depths of Your judgments, who can search them out, O Savior of souls, my Savior? Do not disdain me Your handmaiden, O You who are boundless in mercy."
On this day members of the church receive Holy Unction after receiving Holy Communion at the Presanctified Liturgy on Wednesday evening.
It is on account of the agreement made by Judas to betray Jesus on this day that Orthodox Christians fast on Wednesdays (as well as Fridays) throughout the year.