Here it is: Tutorial for a traditional cast on from a village called Ånäset in northern Sweden. This lady said her grandmother taught her to cast on like this and she says she's never found a cast on method she likes better. You end up with an extra "rope" along the edge, and a little purl-pearl row on each side. It is a complication of the ordinary long tail cast on, but the result is far more decorative, flat and stretchy. I like and will use. Now - pictures!
(All images are clickable for bigger versions as usual.)
You start with a loop around your needle as usual, tail hanging down, ball of yarn above.
With thumb and index finger between threads you tilt your hand to create two loops. One around the thumb and one around the index finger.
I'll refer to these two loops in this tutorial as shown above. Thumb loop in red, index loop in yellow. In the photo the needle tip points to the Upper half of the Thumb loop.
Bring needle under both halves of thumb loop.
Come back above the upper half of the thumb loop and dip needle into it.
Bring the needle up over the thumb loop.
Dip into the index loop fetching the lower half of this loop. This thread will be the stitch saved around the needle. Now you just need to find your way out of the thumb loop again, bringing the thread from the lower half of the index loop with you.
Tilt your hand and bring the thread over the lower half of the thumb loop.
This photo isn't as clear as I'd have wanted but what you do is: Wriggle the stitch out of the thumb loop by bringing it through the loop from the backside. Coming out around the upper half of the thumb loop. (With your hand tilted like this you should be able to see "the way out")
Now just release and pull, and you should have one stitch on the needle. Now repeat a few times and you should have a neat row looking like this:
Please try it and let me know if this tutorial was understandable! (If not I'll try a movieclip next time).
Edit: I was just told that this might be a cast on presented in books as a "traditional Norwegian cast on", and it certainly sounds credible. However it may be, it's a clever one.