3 kills - UAV Recon: Use it and you can see the enemies at red dots on your mini radar !
4 kills - Care Package: Give you a smoke bomb, throw it and a box will appear after 5 secs. In the box, we will have full ammo/ or another killstreak.
4 kills - Counter-UAV: Disable enemies's radar.
The rewards are random ( 50% of getting CP, 50% of getting C-U)
5 kills - Predator Missile: I don't have any idea about this killstreak, maybe... controlable missile ?
5 kills - Sentry Gun: Give you a smoke bomb ( like CP), throw it and a sentry gun will appear after 5 secs ( and it's moveable)
6 kills - Precision Strike: Smoke bomb the place you want to blow, then throw it, ka-boom.
7 kills - Harrier Strike: Like Precision Strike, but bigger explosion, and bonus: after the smoke disappear, leave a mark. Any dude get close to that mark will be shot ( 1 shot = 20 hp, with firing sound). The mark will disappear after 45 secs).
7 kills - Attack Helicopter: Use it and you can have 4 random marks on the map. Just like HStr, dudes will get shot if they get close to marks :D.
8 kills - Emergency Airdrop: 4 care packages at a time !
9 kills - Pave Low: Attack Helicopter with bigger damage ( 1 shot = 50 hp), 5 marks.
9 kills - Stealth Bomber: Precision Strike with x2 range.
11 kills - Chopper gunner: Fun part, you can control a helicopter, flying around the map, shooting minigun with your left mouse, shooting a missile with right mouse, but only for 40 secs.
15 kills - EMP: The electromagnetic pulse, no more killstreak for 1 min ( except the dude use who use it).
25 kills - Tactical Nuke: 10 secs after you use it, the whole map explode, everybody die, and you win.