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