Floating Ammo
Note: This is kind of an add-on to the floating mines cheat. There is a way to not only float mines, but different ammo, too. First, turn on all guns (invincibility if you have it because there will be a lot of explosions) and go to the bunker (it doesn't matter which one, just not multiplayer). Now plant mines on four of the eight monitors hanging from the ceiling in the main operation room, and detonate them. Now, as you know, whenever you release any type of mine, it will float in mid-air. But now try throwing knives and hand grenades! Now try shooting grenades with the launcher and shooting rockets with the tanks and the launcher. As you notice, they can all float. If you shoot a floating grenade or rocket, it will blow up and may cause a chain reaction.

Super Fast Glitch
Turn on Fast Animation, Turbo, and invincibility helps. Anyway go to the Cradle and then go to the control console and blow it up. Then follow Trevelyan. It's funny!! He runs all over the place REALLY fast. It's especially funny when he runs down a slope. He actually flies down it, literally. :)... Now kill him and then go to the last part (the antennae thingy that you kill Trevelyan on) then let James jump to the helicopter. He will fly off without it! Then he will stop in mid-air and wait for it. :)

Archive Glitch
This is not useful but it's pretty neat In the Military Archive after you find Natalya and completed all the objectives go to the library to escape. Blast the window but don't jump out. Instead, turn around and look at Natalya. Then quickly shoot and kill her then jump out the window. If you do it quickly and completed all the objectives you should see just yourself running down the ally but no Natalya, yet you will also still beat the level.

Floating Mines Everywhere
This code allows you to float mines anywhere! First go to the bunker in battle mode, make sure you have remote mines as your weapon. Plant eight mines on the TVs that hang from the ceiling. After every TV has a mine on it go to the detonator and blow them all up. Now refill on mines and toss one. Nothing happens, but if you back up you will see a mine floating! You can plant mines anywhere in the Bunker after the code has been done.

Computer on Wall Glitch
First go to the first surface level, then kill the enemies in front of the two cabins one to the right and left), go in the cabin on the right. Look through the window on the door and get out the sniper rifle. Then shoot out all the windows on the other cabin. Instantly a computer should show up on the wall of the cabin you shot the windows out of.

Floating Lock Trick
To do this glitch you must first put the Enemy Rockets Cheat on then go to the Arkangelesk Dam (Level 1) kill some enemies and grab their rockets, then head for the gate with a lock on it towards the end of the level get your rockets out and shoot one at the gate's lock and when the smoke clears there will be a broken lock floating in mid-air!

Weird Stuck-in-the-Wall Glitch
I came across this little glitch on accident. Once you get the Cougar Magnum code, use it to play the first level, the Dam. When you get to the two guards inside a barrier shooting at you through a small hole, sneak up around them and shoot the one on the left with the Magnum. The guard will fall backwards and then jump right up the wall and slip through the hole they were shooting you through! When I did it, I didn't get a fatal hit the first time, so he got up and came back down through the hole again. I shot him and he got stuck again but this time he stayed there!

Waxed Battle Floors
I've found a cool glitch in Battle Mode (Any type). Just simply have one person kneel and go in front of another person. The kneeling person will be sliding on their foot and knee. It's pretty cool.

Truck Glitch
In the first level, when you open the security gates for the truck, if you walk too close to the car in front of it, it's possible to get stuck. The truck will then stop and trap you. You can still shoot and turn, but you can't move.

Warping Natalya Glitch
This may not be "useful", but it's still fun! In the Statue Park (level 10) rescue Natalya from the plane, and quickly run to where the flight recorder would be after the plane explodes. When you get it, run to the gates where Natalya would be being held prisoner. As you run to the gate, you should see another Natalya running to the gate as you instructed her to do so.