The The Secret Armory of General Knoxx Add-on for Borderlands has 10 achievements.
Destroyed the Lance Depot
Killed each of the loot midgets
Rescued Athena
Destroyed a Lancer while in a Racer
Built the New Car: Monster
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