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