Empty City
This is an odd glitch my friend discovered entirely by accident, what it does is leave the city completely bare as none of the people or vehicles are loaded, aside from warzone areas and such.
Once you acquire the Hammertoss ability for the Hammerfist power, find your way into a military base.
Clear out the base of enemies and vehicles.
The tricky part is here, watch the video of the me doing the glitch and note the area of the beams that I toss myself into.
Run and hammertoss into that exact location and you'll know if you did it right when Alex is halfway outside of the wall right above the spot.
This part is entirely inconsistent and I have not yet been able to figure out how it works. Usually when I execute the glitch perfectly(which I've only done thrice), it happens very quickly and I can not see how it really forces you through the wall.
Slowly walk up the slope and mess with the camera and you will most likely get it on your own, other than that I can't explain much more.
Guaranteed to work on PC/360.