The The Secret Armory of General Knoxx Add-on for Borderlands has 10 achievements.
Paid for a worthless tour of the world's largest bullet
Completed all missions in Secret Armory
Killed each of the loot midgets
Killed Crawmerax the Invincible
Rescued Athena
Destroyed the Lance Depot
Destroyed a Lancer while in a Racer
Built the New Car: Monster
Reached Level 61
Reached Level 51