The cleansing of the temple
John places the temple cleansing at the start of the ministry, the Synoptics at the end — one event placed differently, or two cleansings.
John 2:13-22
13The Passover of the Jews was at hand, and Jesus went up to Jerusalem.
14He found in the temple those who sold oxen, sheep, and doves, and the changers of money sitting.
15He made a whip of cords, and threw all out of the temple, both the sheep and the oxen; and he poured out the changers’ money and overthrew their tables.
16To those who sold the doves, he said, “Take these things out of here! Don’t make my Father’s house a marketplace!”
17His disciples remembered that it was written, “Zeal for your house will eat me up.”
18The Jews therefore answered him, “What sign do you show us, seeing that you do these things?”
19Jesus answered them, “Destroy this temple, and in three days I will raise it up.”
20The Jews therefore said, “It took forty-six years to build this temple! Will you raise it up in three days?”
21But he spoke of the temple of his body.
22When therefore he was raised from the dead, his disciples remembered that he said this, and they believed the Scripture, and the word which Jesus had said.
Mark 11:15-18
15They came to Jerusalem, and Jesus entered into the temple, and began to throw out those who sold and those who bought in the temple, and overthrew the money changers’ tables, and the seats of those who sold the doves.
16He would not allow anyone to carry a container through the temple.
17He taught, saying to them, “Isn’t it written, ‘My house will be called a house of prayer for all the nations?’ But you have made it a den of robbers!”
18The chief priests and the scribes heard it, and sought how they might destroy him. For they feared him, because all the multitude was astonished at his teaching.
What each tradition says
Rabbinic / Midrashic
According to this source, Jesus was moved to action by indignation at seeing the Temple hill turned into a poultry and cattle market for the benefit of the arrogant hierarchy. He attacked the "bazaars of the Hananites," called it with Jeremiah "a den of thieves," seized the money-changers' tables, and drove their owners out of the Temple.
Joseph Jacobs, Kaufmann Kohler, Richard Gottheil, Samuel Krauss, The Jewish Encyclopedia (Funk & Wagnalls, 1901-1906), s.v. 'Jesus of Nazareth' — section 'His Death', opening paragraph
Patristic
Augustine says this act was performed by the Lord not once but twice. John records only the first instance, while the other three Gospels record the last.
Augustine of Hippo (354-430), The Harmony of the Gospels (trans. S. D. F. Salmond), in NPNF ser. 1, vol. 6 (ed. Philip Schaff; T&T Clark, Edinburgh, 1888) — Book II, ch. 67 ('Of the Expulsion of the Sellers and Buyers from the Temple')
Catholic
Anthony Maas states that on Monday Jesus curses the barren fig tree. During the morning, he drives the buyers and sellers from the Temple.
Anthony Maas, The Catholic Encyclopedia, vol. 8, s.v. 'Chronology of the Life of Jesus Christ' (New York: Robert Appleton Company, 1910) — section 'Ninth journey' (Holy Week)
Orthodox
Chrysostom holds that John and the Synoptics do not contradict each other. Rather, Christ cleansed the temple twice: once at the beginning of His ministry, and again when He had come to the very time of His Passion. These were not the same occasion.
John Chrysostom (c. 349-407), Homilies on the Gospel of St. John, in NPNF ser. 1, vol. 14 (ed. Philip Schaff; T&T Clark, Edinburgh, 1889) — Homily XXIII (on John ii. 11), exposition of verses 13-17
Reformed / Protestant
Calvin says the other three also relate what Christ did here, but the difference in time shows it was a similar event, not the same. He therefore holds that Christ cleansed the temple twice: once when beginning his commission, and once when he was about to leave the world.
John Calvin (1509-1564), Commentary on the Gospel according to John, vol. 1 (trans. William Pringle; Calvin Translation Society, Edinburgh, 1847) — comment on John 2:13-16
Evangelical
Albert Barnes says this cleansing took place at the beginning of his public ministry, and that another took place at the close. On each occasion he showed great regard for the pure worship of his Father; one design of his coming was to reform abuses in that worship and bring people to proper regard for God's glory.
Albert Barnes (1798-1870), Notes on the New Testament, Explanatory and Practical (enlarged ed. by Robert Frew; CCEL carries the Baker reprint) — Note on John 2:14