Here is the most up-to-date timeline that I've seen, and it *looks* to be the most accurate:
Dragon Age II - Hindsight Hundreds of Years Ago (Short Story / Flash Comic)
Dragon Age - The Stolen Throne 8:97 - 8:99 BA (9:10 DA) (Novel)
Dragon Age - The Calling 9:10 - 9:11 DA (Novel)
Dragon Age - Journeys: The Deep Roads 9:13 DA (Flash Game - Browser)
Dragon Age II - Sebastian 9:22 DA (Short Story)
Dragon Age II - Aveline: "Focus" 9:25 DA (Short Story)
Dragon Age - Origins: Leliana's Song 9:28 DA (PC/Xbox 360/PS3 - Campaign)
Dragon Age #1-6 (9:12 - 9:13 DA) 9:30 DA (Comic Book Mini-Series - IDW Publishing)
Dragon Age Set 1: "The Dalish Curse" 9:30 DA (RPG - Set 1, Levels 1-5)
Dragon Age "A Bann Too Many" 9:30 DA (RPG - Game Master's Kit)
Dragon Age "An Arl's Ransom" 9:30 DA (RPG - Quickstart Guide)
Dragon Age "Amber Rage" 9:30 DA (RPG - Adventure Book 1, Scenario 1)
Dragon Age "Where Eagles Lair" 9:30 DA (RPG - Adventure Book 1, Scenario 2)
Dragon Age "A Fragile Web" 9:30 DA (RPG - Adventure Book 1, Scenario 3)
Dragon Age Set 2: "The Autumn Falls" 9:30 DA (RPG - Set 2, Levels 6-10)
Dragon Age - The Deep Roads 9:30 DA (RPG - Adventure Book 2)
Dragon Age - Set 3 9:30 DA (RPG - Set 3, Levels 11-20)
Dragon Age - Origins 9:30 DA (Comic - Online)
Dragon Age - Origins: A Tale of Orzammar 9:30 DA (PC - Demo / Campaign)
Dragon Age - Origins 9:30 - 9:31 DA (PC/Xbox 360/PS3)
Dragon Age - Origins: The Stone Prisoner 9:31 DA (PC/Xbox 360/PS3 - Add-On)
Dragon Age - Origins: Warden's Keep 9:31 DA (PC/Xbox 360/PS3 - Add-On)
Dragon Age - Origins: Return to Ostagar 9:31 DA (PC/Xbox 360/PS3 - Add-On)
Dragon Age - Origins: The Revelation 9:31 DA (Comic - Online)
Dragon Age - Warden's Fall, Part 1-5 9:31 DA (Short Film - Machinima)
Dragon Age - Origins: Awakening 9:31 DA (Comic - Online)
Dragon Age - Origins: Awakening 9:31 DA (PC/Xbox 360/PS3 - Expansion)
Dragon Age - The Golems of Amgarrak 9:31 DA (PC/Xbox 360/PS3 - Campaign)
Dragon Age II - Anders 9:31 DA (Short Story)
Dragon Age II - Isabela 9:31 DA (Short Story)
Dragon Age II - Merrill 9:31 DA (Short Story)
Dragon Age II - Fenris 9:31 DA (Short Story)
Dragon Age - Origins: Witch Hunt 9:32 DA (PC/Xbox 360/PS3 - Campaign)
Dragon Age - Dawn of the Seeker 9:?? DA (DVD/Blu-Ray - Anime Movie)
Dragon Age II 9:34 DA (Comic - Online)
Dragon Age - Asunder 9:38 DA (Novel)
Dragon Age II (9:30 - 9:31 / 9:34 / 9:37 DA) 9:40 DA (PC/Xbox 360/PS3)
Dragon Age II: The Black Emporium (9:31 / 9:34 / 9:37 DA) 9:40 DA (PC/Xbox 360/PS3 - Add-On)
Dragon Age II: The Exiled Prince (9:31 / 9:34 / 9:37 DA) 9:40 DA (PC/Xbox 360/PS3 - Add-On)
Dragon Age II: Legacy (9:31 / 9:34 / 9:37 DA) 9:40 DA (PC/Xbox 360/PS3 - Add-On)
Dragon Age II: Mark of the Assassin (9:31 / 9:34 / 9:37 DA) 9:40 DA (PC/Xbox 360/PS3 - Add-On)
Dragon Age - Redemption, Part 1-6 9:40 DA (Short Film - Online)
Dragon Age - Legends 9:40 DA (Flash Game - Facebook)
Dragon Age #1 9:?? DA (Comic Book Mini-Series - Dark Horse)
Admiral Yacob wrote:9:32 Awakenings (2 years after the end of DAO)
Awakenings may be in 9:31. Awakenings is only 6 months after the end of Origins. If it were 2 years after, then Anders would still be in Ferelden and not Kirkwall.

And the introduction to DA2 is concurrent with DA:O. Lothering is approximately one month after Ostagar. The first chapter in Kirkwall is probably only a short time after the events of Awakenings --- which shoots the timeline of Anders all to poo.
*** Edited to add: timeline taken from Bioware social forums (I think) ***