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