Full list of all 80 Borderlands Game of the Year Enhanced achievements. It takes around 60-80 hours to unlock all of the achievements on Windows.
Found all 6 Claptrap statues
Killed each of the loot midgets
Rescued enough Claptraps to earn 42 inventory slots
Completed the larger challenge in The Gully coliseum
Destroyed Lance Depot
Destroyed a Lancer while in a Racer
Rescued Athena
Built the New Car: Monster
Completed all missions in the Arid Badlands
Completed the lesser challenge in all 3 coliseums
Completed the "Braaaaaaaaaaaaains!" mission
Killed Ned. Again.
Killed Ned...sort of
Completed the "Jakobs Fodder" mission
Completed the "House of the Ned" mission
Emerged victorious from an arena match
Raced around the Ludicrous Speedway in record time
Completed a crazy request for Tannis
Killed the Interplanetary Ninja Assassin Claptrap
Killed Commandant Steele-trap
Killed Dr. Ned-trap
Killed General Knoxx-trap
Earned level 40
Completed all missions in the Rust Commons
Killed the Vault Boss
Discovered Eridian Promontory
Discovered Crimson Lance Enclave
Killed Flynt
Killed 5 Rakk in under 10 seconds
Killed the Rakk Hive
Discovered Trash Coast
Earned $1,000,000
Earned level 30
Killed Krom
Killed 25 enemies with corrosive weapons
Discovered Krom's Canyon
Mastered the technology of Pandora
Reached proficiency level 10 with any weapon type
Discovered The Scrapyard
Killed 25 enemies with incendiary weapons
Won a duel against another player
Won a duel without taking damage
Completed 5 missions in the Rust Commons
Sold 50 guns to a shop
Earned level 20
Killed 25 enemies by ramming them with any vehicle
Equipped a class mod for your character
Killed Sledge
Defeated the Rakk Hive, the Vault Boss, Sledge, Krom, or Flynt in a co-op game
Killed 25 enemies with shock weapons
Applied an elemental artifact
Discovered Headstone Mine
Killed 25 enemies with explosive weapons
Discovered Sledge's Safe House
Earned level 10
Killed an enemy with the Siren's action skill
Completed 15 missions in co-op
Rescued a groupmate from death in a co-op game
Earned level 5
Discovered Skag Gully
Completed 5 missions in the Arid Badlands
Killed an enemy plumber-style
Play with at least two other players.
Earned level 50
I bet you never thought you'd be here
Killed 15 enemies with the Hunter's action skill
Killed 15 enemies with the Berserker's action skill
Killed 15 enemies with the Soldier's action skill
Completed the larger challenge in the Hell-Burbia coliseum
Completed the larger challenge in The Angelic Ruins coliseum
Completed each of the larger challenges in all 3 coliseums
Killed Crawmerax the Invincible
Reached Level 51
Reached Level 61
Completed all missions in Secret Armory
Paid for a worthless tour of the world's largest bullet
Found 25 oil cans
Collected 15 Claptrap bobbleheads
Collected 5 3D glasses
Collected 3 panties, 5 fish in a bag, and 15 pizzas