I'm a self-taught knitter, and people often remark on the way that I knit. In terms of in which hand I hold the yarn, I am an English knitter or 'thrower', but I hold my needles a bit differently. I 'anchor' my needles against my body - against my thigh for long straights, and against my belly or chest for circs & DPNs.
It wasn't until some time later that I learned my knitting style has a name - supported knitting, which covers several styles of anchoring - against your belly, waist, thigh, in your armpit (sometimes called 'pit knitting'), or knitting using a knitting belt or sheath.
Knitting sheaths are an old tool, hardly used since the beginning of the Victorian era (though gaining in popularity - thanks to online communities such as Ravelry). They are firm sheaths that support the needle at the waist. Knitting belts are a different tool, but with the same purpose - a pliable belt (of leather, etc), with holes in for placing the needles. I have actually considered getting a knitting belt, because when I knit with DPNs (and I like the sharp ones), sometimes I get poked!
There is some empirical evidence for the increased efficiency of supported knitting styles, over other ones. (via A Fisherman Knits:)
A knitting needle is a lever for moving yarn. In most modern knitting techniques, the mechanical advantage is about 1: 3, with the fingers/ thumb of the hand providing both the force and acting as the fulcrum of the lever. This places stress on the hands and wrists. When the needle is inserted into a knitting sheath, the knitting sheath becomes the fulcrum and the force is applied with a 1:50 mechanical advantage. In addition, the knitting sheath allow the forced to be generated by the large muscles of the shoulders and transmitted through the very strong tendons of the upper arm.
How did my own style come about? Necessity, really. While I was learning to knit (from books, where only the tips of the needles and stitches are ever pictured!), I couldn't bother trying to balance both needles at the same time. So, the right needle came to rest on my body, while I moved the stitches with the left needle and wrapped with my right hand. Over time, my style has evolved and nowadays I'm a quite fast knitter, comparatively.
Even though I hold the yarn in my right hand, I don't actually 'throw' - more like 'flicking'. My hands never leave the needles - my right pinky and ring finger support the working needle while my middle, forefinger and thumb tension the yarn and bring it around to wrap. The left hand does the moving, bringing the stitches over to the working needle.
People generally say that continental knitting (left-handed) is faster than English knitting (right-handed), which is generally true, except for in the case of supported knitting - some of the fastest knitters in the world knit supported, such as Hazel Tindall (video - very similar to how I knit). (More on speed knitting here)