This list (taken from Wikipedia) is a collection of deeds of varying degrees of offensiveness that have been compiled by religious scholars after Mohammed's time, according to the beliefs of their respective periods. The deeds are interpreted as implied by the canon of the Qur'an.
1. Associating anything with Allah
2. Murder
3. Practising magic
4. Not Praying
5. Not paying Zakat
6. Not fasting on a Day of Ramadan without excuse
7. Not performing Hajj, while being able to do so
8. Disrespect to parents
9. Abandoning relatives
10. Fornication and Adultery
11. Homosexual relations (sodomy), but not homosexuality as its a "state" not an act.
12. Usury (Riba)
13. Wrongfully consuming the property of an orphan
14. Lying about Allah and His Messenger
15. Running away from the battlefield
16. A leader's deceiving his people and being unjust to them
17. Pride and arrogance
18. Bearing false witness
19. Drinking Khamr (liquor)
20. Gambling
21. Slandering chaste women
22. Stealing from the spoils of war
23. Stealing
24. Highway Robbery
25. Taking false oath
26. Oppression
27. Illegal gain
28. Consuming wealth acquired unlawfully
29. Committing suicide
30. Frequent lying
31. Judging unjustly
32. Giving and Accepting bribes
33. Woman's imitating man and man's imitating woman
34. Being cuckold
35. Marrying a divorced woman in order to make her lawful for the husband
36. Not protecting oneself from urine
37. Showing-off
38. Learning knowledge of the religion for the sake of this world and concealing that knowledge
39. Bertrayal of trust
40. Recounting favours
41. Denying Allah's Decree
42. Listening (to) people's private conversations
43. Carrying tales
44. Cursing
45. Breaking contracts
46. Believing in fortune-tellers and astrologers
47. A woman's bad conduct towards her husband
48. Making statues and pictures
49. Lamenting, wailing, tearing the clothing, and doing other things of this sort when an affliction befalls
50. Treating others unjustly
51. Overbearing conduct toward the wife, the servant, the weak, and animals
52. Offending one's neighbour
53. Offending and abusing Muslims
54. Offending people and having an arrogant attitude toward them
55. Trailing one's garment in pride
56. Men's wearing silk and gold
57. A slave's running away from his master
58. Slaughtering an animal which has been dedicated to anyone other than Allah
59. To knowingly ascribe one's paternity to a father other than one's own
60. Arguing and disputing violently
61. Withholding excess water
62. Giving short weight or measure
63. Feeling secure from Allah's Plan
64. Offending Allah's righteous friends
65. Not praying in congregation but praying alone without an excuse
66. Persistently missing Friday Prayers without any excuse
67. Unsurping the rights of the heir through bequests
68. Deceiving and plotting evil
69. Spying for the enemy of the Muslims
70. Cursing or insulting any of the Companions of Allah's Messenger
(See also: First Ten Verses of Surah Al-Mu'minoon)
