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