Talking of other CS "bugs" that have turned into features, anyone who's never seen "surfing" should check that out.
Basically, you take the same air-strafing principles from this article, add a little bunny-hopping, and another "feature" of counterstrike where if you land on a steep enough slope you won't take falling damage or apply friction. Give this to some insane map makers and the end result is an incredibly skill-intensive obstacle course of sorts at tremendously high speeds.
It's used in speedruns, but I believe is fixed these days. Apprently if you're bunnyhopping backwards, the game tries to limit the speed, but since you're going backwards the player ends up accelerating essentially indefinitely.
Basically, you take the same air-strafing principles from this article, add a little bunny-hopping, and another "feature" of counterstrike where if you land on a steep enough slope you won't take falling damage or apply friction. Give this to some insane map makers and the end result is an incredibly skill-intensive obstacle course of sorts at tremendously high speeds.
Here's a good example of what I'm talking about: https://www.youtube.com/watch?v=o0Xv00yJhjs
There's a really dedicated community behind this stuff, you can find 64-man servers full of people playing this type of map in CS:GO and CS:Source.