Sort of like a revamped version of that smart moving mod? I'd like that too. Coupled with waves and a surfboard though, like the yogscast had for that one video.
I used to love surfing games.
A revamped version of Smart Moving, that would feel much more fluid. Instead of going prone all in 1 motion and doing everything in one state to the next, your character and view would shift down to doing that. Also if you were running then did something, you wouldn't all of the sudden stop and do it. you'd keep moving as you transition into that state.