Initially conceived of after a post today in the TOR thread, then made more broad when I figured it could be a more generally useful reference. Wookieepedia has individual pages for timelines of each medium, but the general timeline of media page is still a bit of a mess. So...
Pre-Republic and ancient Republic
36,453 BBY [36,453 years b the Battle of Yavin--the Death Star battle in ANH]
Dawn of the Jedi #0 [comic promotional issue]
Timeline 19: Force "Discovered" on Tython [TOR promotional video]
ca. 25,793 BBY (yes, 10,000 years later)
Dawn of the Jedi [upcoming comic series]
Timeline 18: The Force War on Tython [TOR promotional video]
25,783 BBY -- Timeline 17: The Jedi Order is Established [TOR promotional video]
25,053 BBY -- Timeline 16: Founding of the Republic [TOR promotional video]
ca. 24,953 BBY -- Timeline 15: The Jedi Join the Republic [TOR promotional video]
Old Republic
7000 BBY -- Timeline 14: The 2nd Great Jedi Schism [TOR promotional video]
6900 BBY -- Timeline 13: The First Dark Sith Lords on Korriban [TOR promotional video]
5000 BBY
Tales of the Jedi: The Golden Age of the Sith [comic]
Tales of the Jedi: The Fall of the Sith Empire [comic]
Lost Tribe of the Sith: Precipice [eBook]
Lost Tribe of the Sith: Skyborn [eBook]
Timeline 12: The Great Hyperspace War [TOR promotional video]
4985 BBY -- Lost Tribe of the Sith: Paragon [eBook]
4975 BBY -- Lost Tribe of the Sith: Savior [eBook]
4904 BBY -- Timeline 11: Rebirth of the Sith Empire [TOR promotional video]
4000 BBY
Tales of the Jedi: Ulic Qel-Droma and the Beast Wars of Onderon [comic]
Tales of the Jedi: The Saga of Nomi Sunrider [comic]
Timeline 10: The Exar Kun War [TOR promotional video]
A Tale from the Dark Side [short story]
3998 BBY -- Tales of the Jedi: The Freedon Nadd Uprising [comic]
3997 BBY -- Tales of the Jedi: Dark Lords of the Sith [comic]
3996 BBY -- Tales of the Jedi: The Sith War [comic]
3993 BBY -- Shadows and Light [one-shot comic from Star Wars Tales]
3986 BBY -- Tales of the Jedi: Redemption [comic]
3980 BBY -- Mandorla [novel, to be released Sept 2012]
3964 BBY
Knights of the Old Republic: Crossroads [comic]
Knights of the Old Republic: Commencement [comic]
Knights of the Old Republic: Flashpoint [comic]
Timeline 9: The Mandalorian Wars [TOR promotional video]
3963 BBY
Knights of the Old Republic: Flashpoint Interlude: Homecoming [comic]
Knights of the Old Republic: Reunion [comic]
Labor Pains [short story]
Knights of the Old Republic: Days of Fear [comic]
Knights of the Old Republic: Nights of Anger [comic]
Knights of the Old Republic: Daze of Hate [comic]
Knights of the Old Republic: Knights of Suffering [comic]
Knights of the Old Republic: Vector [comic]
Knights of the Old Republic: Exalted [comic]
Knights of the Old Republic: Turnabout [comic]
Knights of the Old Republic: Vindication [comic]
Knights of the Old Republic: Prophet Motive [comic]
Knights of the Old Republic: Faithful Execution [comic]
Knights of the Old Republic: Dueling Ambitions [comic]
Knights of the Old Republic: Masks [comic]
Knights of the Old Republic: The Reaping [comic]
Knights of the Old Republic: Destroyer [comic]
Knights of the Old Republic: Demon [comic]
Interference [short story]
3962 BBY -- Knights of the Old Republic: War [comic]
3960 BBY -- Lost Tribe of the Sith: Purgatory [eBook]
3960-59 BBY -- Lost Tribe of the Sith: Sentinel [eBook]
3956 BBY
Knights of the Old Republic [video game]
Timeline 8: The Jedi Civil War [TOR promotional video]
3954 BBY -- The Old Republic: Revan [novel, first half only]
3952 BBY -- Unseen, Unheard [one-shot comic from Star Wars Tales]
3951 BBY -- Knights of the Old Republic II: The Sith Lords [video game]
3950 BBY -- The Old Republic: Revan [novel, second half]
3756 BBY -- Timeline 7: Peace for the Republic? [TOR promotional video]
3681 BBY
The Old Republic: Return [TOR cinematic trailer]
Timeline 6: Onslaught of the Sith Empire [TOR promotional video]
3678 BBY -- The Old Republic: Blood of the Empire [comic]
3671 BBY -- Timeline 5: The Battle of Bothawui [TOR promotional video]
3667 BBY -- Timeline 4: The Empire Changes Strategy [TOR promotional video]
3661 BBY -- Timeline 3: The Return of the Mandalorans [TOR promotional video]
3660 BBY
Timeline 2: The Mandalorian Blockade is Broken [TOR promotional video]
The Old Republic: Smuggler's Vanguard [short story]
The Old Republic: Hope [TOR cinematic trailer]
The Old Republic: The Third Lesson [short story]
3653 BBY
The Old Republic: Deceived [TOR cinematic trailer]
The Old Republic: Deceived [novel]
The Old Republic: Threat of Peace [comic]
Timeline 1: Treaty of Coruscant [TOR promotional video]
3645 BBY
Red Harvest [novel]
ca. 3643-41 BBY
The Old Republic: The Lost Suns [comic]
The Old Republic: Fatal Alliance [novel]
The Old Republic [video game]
? BBY -- As-yet untitled 4th TOR novel, to be set after the video game
3000 BBY -- Lost Tribe of the Sith: Pantheon
1032 BBY
Knight Errant: Influx [short story]
Knight Errant: Aflame [comic]
Knight Errant [novel]
Knight Errant: Deluge [comic]
Knight Errant: Escape [upcoming comic]
1003-1000 BBY
Darth Bane: Path of Destruction [novel]
1002 BBY -- Darkness Shared [short story]
1000 BBY
Jedi vs. Sith [comic]
Bane of the Sith [short story]
1000-990 BBY
Darth Bane: Rule of Two
996 BBY -- All for You [one-shot comic from Star Wars Tales]
980 BBY
Darth Bane: Dynasty of Evil
Pre-Republic and ancient Republic
36,453 BBY [36,453 years b the Battle of Yavin--the Death Star battle in ANH]
Dawn of the Jedi #0 [comic promotional issue]
Timeline 19: Force "Discovered" on Tython [TOR promotional video]
ca. 25,793 BBY (yes, 10,000 years later)
Dawn of the Jedi [upcoming comic series]
Timeline 18: The Force War on Tython [TOR promotional video]
25,783 BBY -- Timeline 17: The Jedi Order is Established [TOR promotional video]
25,053 BBY -- Timeline 16: Founding of the Republic [TOR promotional video]
ca. 24,953 BBY -- Timeline 15: The Jedi Join the Republic [TOR promotional video]
Old Republic
7000 BBY -- Timeline 14: The 2nd Great Jedi Schism [TOR promotional video]
6900 BBY -- Timeline 13: The First Dark Sith Lords on Korriban [TOR promotional video]
5000 BBY
Tales of the Jedi: The Golden Age of the Sith [comic]
Tales of the Jedi: The Fall of the Sith Empire [comic]
Lost Tribe of the Sith: Precipice [eBook]
Lost Tribe of the Sith: Skyborn [eBook]
Timeline 12: The Great Hyperspace War [TOR promotional video]
4985 BBY -- Lost Tribe of the Sith: Paragon [eBook]
4975 BBY -- Lost Tribe of the Sith: Savior [eBook]
4904 BBY -- Timeline 11: Rebirth of the Sith Empire [TOR promotional video]
4000 BBY
Tales of the Jedi: Ulic Qel-Droma and the Beast Wars of Onderon [comic]
Tales of the Jedi: The Saga of Nomi Sunrider [comic]
Timeline 10: The Exar Kun War [TOR promotional video]
A Tale from the Dark Side [short story]
3998 BBY -- Tales of the Jedi: The Freedon Nadd Uprising [comic]
3997 BBY -- Tales of the Jedi: Dark Lords of the Sith [comic]
3996 BBY -- Tales of the Jedi: The Sith War [comic]
3993 BBY -- Shadows and Light [one-shot comic from Star Wars Tales]
3986 BBY -- Tales of the Jedi: Redemption [comic]
3980 BBY -- Mandorla [novel, to be released Sept 2012]
3964 BBY
Knights of the Old Republic: Crossroads [comic]
Knights of the Old Republic: Commencement [comic]
Knights of the Old Republic: Flashpoint [comic]
Timeline 9: The Mandalorian Wars [TOR promotional video]
3963 BBY
Knights of the Old Republic: Flashpoint Interlude: Homecoming [comic]
Knights of the Old Republic: Reunion [comic]
Labor Pains [short story]
Knights of the Old Republic: Days of Fear [comic]
Knights of the Old Republic: Nights of Anger [comic]
Knights of the Old Republic: Daze of Hate [comic]
Knights of the Old Republic: Knights of Suffering [comic]
Knights of the Old Republic: Vector [comic]
Knights of the Old Republic: Exalted [comic]
Knights of the Old Republic: Turnabout [comic]
Knights of the Old Republic: Vindication [comic]
Knights of the Old Republic: Prophet Motive [comic]
Knights of the Old Republic: Faithful Execution [comic]
Knights of the Old Republic: Dueling Ambitions [comic]
Knights of the Old Republic: Masks [comic]
Knights of the Old Republic: The Reaping [comic]
Knights of the Old Republic: Destroyer [comic]
Knights of the Old Republic: Demon [comic]
Interference [short story]
3962 BBY -- Knights of the Old Republic: War [comic]
3960 BBY -- Lost Tribe of the Sith: Purgatory [eBook]
3960-59 BBY -- Lost Tribe of the Sith: Sentinel [eBook]
3956 BBY
Knights of the Old Republic [video game]
Timeline 8: The Jedi Civil War [TOR promotional video]
3954 BBY -- The Old Republic: Revan [novel, first half only]
3952 BBY -- Unseen, Unheard [one-shot comic from Star Wars Tales]
3951 BBY -- Knights of the Old Republic II: The Sith Lords [video game]
3950 BBY -- The Old Republic: Revan [novel, second half]
3756 BBY -- Timeline 7: Peace for the Republic? [TOR promotional video]
3681 BBY
The Old Republic: Return [TOR cinematic trailer]
Timeline 6: Onslaught of the Sith Empire [TOR promotional video]
3678 BBY -- The Old Republic: Blood of the Empire [comic]
3671 BBY -- Timeline 5: The Battle of Bothawui [TOR promotional video]
3667 BBY -- Timeline 4: The Empire Changes Strategy [TOR promotional video]
3661 BBY -- Timeline 3: The Return of the Mandalorans [TOR promotional video]
3660 BBY
Timeline 2: The Mandalorian Blockade is Broken [TOR promotional video]
The Old Republic: Smuggler's Vanguard [short story]
The Old Republic: Hope [TOR cinematic trailer]
The Old Republic: The Third Lesson [short story]
3653 BBY
The Old Republic: Deceived [TOR cinematic trailer]
The Old Republic: Deceived [novel]
The Old Republic: Threat of Peace [comic]
Timeline 1: Treaty of Coruscant [TOR promotional video]
3645 BBY
Red Harvest [novel]
ca. 3643-41 BBY
The Old Republic: The Lost Suns [comic]
The Old Republic: Fatal Alliance [novel]
The Old Republic [video game]
? BBY -- As-yet untitled 4th TOR novel, to be set after the video game
3000 BBY -- Lost Tribe of the Sith: Pantheon
1032 BBY
Knight Errant: Influx [short story]
Knight Errant: Aflame [comic]
Knight Errant [novel]
Knight Errant: Deluge [comic]
Knight Errant: Escape [upcoming comic]
1003-1000 BBY
Darth Bane: Path of Destruction [novel]
1002 BBY -- Darkness Shared [short story]
1000 BBY
Jedi vs. Sith [comic]
Bane of the Sith [short story]
1000-990 BBY
Darth Bane: Rule of Two
996 BBY -- All for You [one-shot comic from Star Wars Tales]
980 BBY
Darth Bane: Dynasty of Evil