Here is the full list of all 80 Borderlands: Game of the Year Edition achievements worth 1,750 gamerscore.
Completed the larger challenge in The Angelic Ruins coliseum
Completed each of the larger challenges in all 3 coliseums
Completed the larger challenge in The Gully coliseum
Completed the larger challenge in the Hell-Burbia coliseum
Emerged victorious from an arena match
Completed a crazy request for Tannis
Completed the lesser challenge in all 3 coliseums
Found all 6 Claptrap statues
Killed the Interplanetary Ninja Assassin Claptrap
Killed Commandant Steele-trap
Killed Dr. Ned-trap
Killed General Knoxx-trap
Rescued enough Claptraps to earn 42 inventory slots
Reached Level 61
Killed each of the loot midgets
Completed all missions in Secret Armory
I bet you never thought you'd be here
Killed 15 enemies with the Soldier's action skill
Mastered the technology of Pandora
Killed 25 enemies with shock weapons
Killed 25 enemies with corrosive weapons
Sold 50 guns to a shop
Destroyed Lance Depot
Rescued Athena
Destroyed a Lancer while in a Racer
Paid for a worthless tour of the world's largest bullet
Built the New Car: Monster
Killed the Vault Boss
Discovered Eridian Promontory
Completed all missions in the Rust Commons
Discovered Crimson Lance Enclave
Killed Flynt
Killed Krom
Discovered Krom's Canyon
Discovered The Scrapyard
Reached Level 51
Earned level 50
Completed 5 missions in the Rust Commons
Won a duel against another player
Won a duel without taking damage
Completed 15 missions in co-op
Earned level 40
Killed 25 enemies with explosive weapons
Raced around the Ludicrous Speedway in record time
Completed all missions in the Arid Badlands
Equipped a class mod for your character
Killed Sledge
Discovered Headstone Mine
Killed 25 enemies with incendiary weapons
Killed 25 enemies by ramming them with any vehicle
Applied an elemental artifact
Discovered Sledge's Safe House
Earned level 20
Rescued a groupmate from death in a co-op game
Defeated the Rakk Hive, the Vault Boss, Sledge, Krom, or Flynt in a co-op game
Killed the Rakk Hive
Discovered Trash Coast
Killed 5 Rakk in under 10 seconds
Killed 15 enemies with the Hunter's action skill
Earned level 30
Killed Crawmerax the Invincible
Reached proficiency level 10 with any weapon type
Earned level 10
Played with at least two other players.
Earned level 5
Discovered Skag Gully
Killed an enemy plumber-style
Completed 5 missions in the Arid Badlands
Completed the "Braaaaaaaaaaaaains!" mission
Killed Ned. Again.
Killed Ned...sort of
Completed the "Jakobs Fodder" mission
Completed the "House of the Ned" mission
Collected 15 Claptrap bobbleheads
Collected 3 panties, 5 fish in a bag, and 15 pizzas
Collected 5 3D glasses
Found 25 oil cans
Killed an enemy with the Siren's action skill
Killed 15 enemies with the Berserker's action skill
Earned $1,000,000