I found an interesting little bug in single player...
(Although I'm sure someone else found it ages ago)
Well, you may be wondering what it is, but I'm going to make you read this part curiously, and most importantly; pointlessly. Behold my unnecessary text.
Anyways; when using "Air Friction", if you land at the moment it activates (by free-falling with a precise amount of air-time), it launches you in the air, roughly about 1.6x normal "power jump" height.
On top of this, if you time it just right, you can use a "power jump" on top of this,
and reach ridiculous heights, escape maps, jump on top of churches, ect.
It's most easily done by using a normal jump off a shipping crate onto flat ground.
(which is common throughout the campaign).
So, is this old?
If not, try it. It's fun.
This video only shows the first half of the trick. You need to do the second half (read above) to use it's potential.