There was another post like this but this method is much more efficient, and I didn't really want to necro the thread.
First of all, this doesn't work everywhere, it seems to only work in non PvP areas (cities), and/or crowded areas. It's also pretty damn simple and I'm actually suprised it works.
: While you are sprinting regularly, hold down the right mouse button and start making little circles with your mouse(they don't have to big enough to make you actually do a zigzag, just a small circle) and viola.
Some things I've noticed from this is that it is very hard to turn corners without losing some stamina, and sometimes your stamina will randomly go down while running, but if you do it right its pretty much unlimited.
I also found an instant cast glitch that works kind of like this one, but I won't be releasing that until I can figure out how to get it to work more often.
Here's a small video if you can't figure it out..
AoC.wmv