I have been making this crocheted blanket:
http://www.feltedbutton.com/2014/03/spring-into-summer-with-free-crochet.html
...a
lot for baby blankets over the last... (checks
Ravelry) year and some.
I've also been modifying it for scarves, a rectangular blanket, and, most recently, a shawl.
For the shawl, it was a mash-up of this pattern with another pattern I'd developed myself, which creates a shawl in an equal-armed L, or right-angled V.
The original shawl's dimensions are essentially five blocks of X" square each, so that it's three squares in each direction. I tend to use 18" squares.
I started in the corner, as for the blanket -- (1) on the diagram below.
I continued until I'd reached the point where the sides of the triangle were each twice 18" (18" being my square size / basic unit of measure for this shawl) -- (2) on the diagram below.
Then I determined where the half-way point of the long edge, or working edge, was, and put a stitch marker there.
I continued from where I was, stopping when I reached the stitch marker -- turning and decreasing on the "inside," and turning and increasing on the "outside."
When the "outside" / increase edge got to 3 x 18", I started decreasing on both sides.
Then I went back to the other arm, and did the same thing there. (No seams necessary!)
It was a lot of fun to make, and I'm looking forward to experimenting with this some more. If you try this modification, I hope you have fun and like the resulting shawl! Enjoy.