A list of cheats for PC version and Xbox 360 version.
Ebony Mail (”Boetiah’s Calling” quest)
Location: Find Sacellum of Boethiah in the east section of Windhelm. You will find a cult, and then begin the quest. To offer the sacrifice, you will have to trap someone in that chamber. An easy way to do this is hire a mercenary (you can visit Bee and Brab in Riften; one is sitting downstairs), and ask him to touch the beacon. Successfully complete the remaining task to get the artifact.
Mace Of Molag Bal (”House Of Horrors” quest in Markarth)
Location: In the city, when you walk past an old haunted house, you will be asked to go with someone. If you complete this task and find the priest of Boethiah, you will get the artifact.
Masque Of Clavicus Vile (”A Daedra’s Best Friend” quest)
Location: The guard at the entry point of Falkreath will tell you about a missing dog. After speaking with him, start the quest. You can follow the dog, or simply go to Haemar’s Shame, which is just south of the large mountain and just east to Helgen. Get the axe, and return it to get the artifact.
Mehrunes’ Razor (”Pieces Of The Past” quest)
Location: Visit the museum in Dawnstar (the message pops up multiple times), accept the quest, and then collect the three pieces of the sword throughout Skyrim to get the artifact.
Oghma Infinium (”Discearning The Transmundane” quest)
Location: When you meet Septimus Sigmus during a main quest, you will be assigned a task to get the Elder Scrolls. You will start the second task (”Discearning The Transmundane”). During this quest, you take the imprint of the Scrolls on the Lexicon. Then, you need the harvested blood from an Orc, Dark Elf, Wood Elf, High Elf, and Falmer. If you do not already have samples from them, you must find them, and kill at least one to harvest the blood. You can visit the Bandit camps for Elf and Orc blood, and you can visit Mzulft (southeast of Windhelm) for Falmers.
Ring Of Namira
Location: Find Verulus in Markarth, and accept his quest, which involves clearing the Necropolis. When Eola starts talking about cannibalism, respond positively. Then, clear the undead from Namira’s altar. Agree to lure Verulus to the Altar. Kill Verulus and eat his flesh, and the Ring Of Namira will appear in your inventory.