In Islam, the Qur'an says that every human being has two angels who follow us around throughout our whole lives. They are known as the "Kiraman Katibeen" which is Arabic for "The Noble Writers."

The Qur'an says in Surah 50: "Behold, two (guardian angels), one sitting on the right and one on the left."

Their only job is to write down and record every action, thought, or feeling we have each day. One figuratively sits on our right shoulder and records all our good deeds and the angel on the left shoulder and records all our bad deeds. It's like God assigned someone to follow you around with a camcorder and record everything you do as evidence.

The Book in which the angels are writing is our cumulative record of deeds. After our death, on the Day of Judgement we will each be confronted with this record, and the two angels will be present with you to tell God of what you did.

God has given us time to repent before these two scribes record our deeds. Muhammad(saw) once said, "The (scribe) on the left hand raises his pen (i.e., delays writing) for six hours (this may refer to six hours of 60 minutes as measured by astronomers, or it may refer to short periods of time during the day or night, according to Lisan al-'Arab) before he records the sinful deed of a Muslim. If [the Muslim] regrets it and seeks God's forgiveness, the deed is not recorded, otherwise it is recorded as one deed." 1. A further respite is granted after the deed has been recorded; up until the moment before death approaches, you are able to repent and ask for forgiveness.

Muhammad once stated:

"After the death of the Muslim, they soar to the heaven and seek permission to live there, but Almighty God turns down their request saying, 'My Heavens are full of Angels who are constantly engaged in Glorifying Me'. Then they will Reply, 'Your creation has filled the earth, constantly glorifying You.' Thereafter, Almighty God will command them to stand at the graveside of the Muslims and the servants of Almighty God to recite "Glory be to God" and prayers, and the reward of which is then bestowed upon the deceased person".

When a Muslim concludes his prayer by turning to his or her right and left shoulders and says "Assalamu Alaikum wa Rahmatullah" (Peace and Mercy of God be upon you), they are greeting the angels, including the writers and any angels who have joined you in prayer.

Muslims often joke with their children that one of their two angels is busy writing. Which one is getting a tired hand?

1. (Reported by at-Tabarani in al-Kabeer and al-Bayhaqi in Shu'ab al-Emaan (The Branches of Faith); classed as hasan by al-Albani in Silsilat al-Ahadeeth al-Saheehah, 1209)

References:
http://www.lse.ac.uk/clubs/islamic/knowledge/tazkiyah/iwtrb.html
http://www.dawateislami.net/services/library/default.asp?bid=2&hid=0&chno=0
Surah al-Infitar (The Cleaving asunder)