It's a simple idea, might not be simple to do. I don't know, really, but here it is. When travelling on a road, a certain type of block that should be changeable, you move slightly faster. This way roads would offer acrtual benefit together with aesthetic value. That's all, simple yet useful and I really really hope this could be done. Feel free to add to the idea.
Client position etc is indeed client side... which is why it has been so easy for people to speedhack.
