Here is the full list of achievements for Borderlands on the Xbox 360. This is just a list of the core game achievements, not achievements for the DLC content.
1.21 Gigawatts (25 points) – Kill 25 enemies with shock weapons
And They’ll Tell Two Friends (10 points) – Play in a co-op game with either an employee of Gearbox or someone who has this achievement
Can’t We Get BEYOND Thunderdome? (25 points) – Win an arena match
Careful, He Bites (15 points) – Kill 15 enemies with the Hunter’s action skill
Ding! Champion (50 points) – Earn level 50
Ding! Expert (20 points) – Earn level 20
Ding! Hardcore (30 points) – Earn level 30
Ding! Newbie (5 points) – Earn level 5
Ding! Novice (10 points) – Earn level 10
Ding! Sleepless (40 points) – Earn level 40
Discovered Crimson Lance Enclave (15 points) – Discover Crimson Lance Enclave
Discovered Eridian Promontory (15 points) – Discover Eridian Promontory
Discovered Headstone Mine (5 points) – Discover Headstone Mine
Discovered Krom’s Canyon (10 points) – Discover Krom’s Canyon
Discovered Skag Gully (5 points) – Discover Skag Gully
Discovered Sledge’s Safe House (5 points) – Discover Sledge’s Safe House
Discovered The Scrapyard (10 points) – Discover The Scrapyard
Discovered Trash Coast (5 points) – Discover Trash Coast
Down in Front! (15 points) – Kill 15 enemies with the Soldier’s action skill
Duel-icious (15 points) – Win a duel against another player
Duelinator (35 points) – Win a duel without taking damage
Facemelter (25 points) – Kill 25 enemies with corrosive weapons
Fence (25 points) – Sell 50 guns to a shop
Fully Loaded (10 points) – Rescue enough Claptraps to earn 42 inventory slots
Get A Little Blood on the Tires (20 points) – Kill 25 enemies by ramming them with any vehicle
Group LF Healer (25 points) – Rescue a groupmate from death in a co-op game
Made in Fyrestone (15 points) – Complete all missions in the Arid Badlands
Made in New Haven (20 points) – Complete all missions in the Rust Commons
Master Exploder (15 points) – Kill 25 enemies with explosive weapons
My Brother is an Italian Plumber (15 points) – Kill an enemy by stomping on its head
Paid in Fyrestone (5 points) – Complete 5 missions in the Arid Badlands
Paid in New Haven (10 points) – Complete 5 missions in the Rust Commons
Pandora-dog Millionaire (50 points) – Earn $1,000,000
Pyro (25 points) – Kill 25 enemies with incendiary weapons
Reckless Abandon (15 points) – Kill 15 enemies with the Berserker’s action skill
Rootinest, Tootinest, Shootinest (10 points) – Kill 5 Rakk in under 10 seconds
Speedy McSpeederton (10 points) – Race around the Ludicrous Speedway in under 31 seconds
There Are Some Who Call Me…Tim (25 points) – Equip a class mod for your character
There’s No “I” In “Team” (30 points) – Complete 15 missions in co-op
Truly Outrageous (15 points) – Kill an enemy with the Siren’s action skill
Weapon Aficionado (20 points) – Reach proficiency level 10 with any weapon type
You Call This Archaeology? (20 points) – Apply an elemental artifact
There are eight secret achievements as well:
12 Days of Pandora (30 points) – Master the technology of Pandora
Destroyed the Destroyer (50 points) – Kill the Vault boss
Destroyed the Hive (40 points) – Kill the Rakk Hive
United We Stand (35 points) – Defeat the Rakk Hive, the Vault Boss, Sledge, Krom, or Flynt in a co-op game
Wanted: Flynt (30 points) – Kill Flynt
Wanted: Krom (20 points) – Kill Krom
Wanted: Sledge (10 points) – Kill Sledge
You’re on a Boat! (15 points) – I bet you never thought you’d be here