The The Secret Armory of General Knoxx Add-on for Borderlands has 9 achievements worth 235 gamerscore.
Complete all missions in Secret Armory
Kill Crawmerax the Invincible
Reach Level 61
Pay for a worthless tour of the world's largest bullet
Destroy the Lance Depot
Kill each of the loot midgets
Destroy a Lancer while in a Racer
Rescue Athena
Build the New Car: Monster