Here is the full list of all 50 Battlefield: Bad Company achievements worth 1,000 gamerscore.
Reached Rank 25
20 Squad members spawned on you and you didn't die!
100 kills using vehicle
Found all collectables
Reached Rank 20
Got at least one kill in every vehicle
Collected 50 unique dog tags
Completed 'Welcome To Bad Company' on hard
Completed 'Acta Non Verba' on hard
Completed 'Crossing Over' on hard
Completed 'Par for the Course' on normal
Completed 'Par for the Course' on hard
Completed 'Air Force One' on normal
Completed 'Air Force One' on hard
Completed 'Crash and Grab' on hard
Found half of all collectables
Completed 'Ghost Town' on hard
Killed 25 enemies in a helicopter
Knocked down a small forest
Destroyed 50 vehicles. (containing enemy AI)
Drove all vehicle types (Jeep, Tank, Heli, Boat)
Hit hostile helicopter with laser designator
Climbed to the highest spot in the game
Knocked down 1000 trees
Played 100 online matches
Placed #1 in a Ranked Match
Collected 5 unique dog tags
Completed one mission without dying (any difficulty)
Completed 'Ghost Town' on normal
Completed 'Crash and Grab' on normal
Used Squad in the menu, found a friend and played one round
There is no parachute, right?
Destroyed 1000 walls
Completed 'Crossing Over' on normal
Completed 'Acta Non Verba' on normal
Reached Rank 8
Took 3 pictures using the image system
Found 5 unique collectables
Destroyed 200 Walls
Used auto Injector 50 Times
Found one gold bar
Completed 'Welcome To Bad Company' on normal
Killed 25 enemies
Reached Rank 3
Played one complete ranked online match
Find half of the gold bars
Find all gold bars
(Online) Achieve all the awards
(Online) Achieve half of all awards
(Online) Get 10002 kills