How about this thing from Rider Wearhouse:
http://www.aerostich.com/off-and-riding/helmets/helmet-accessories/supervisor.html
I have used the SuperVisor on my HJC for 6 years. I use it as my "inbetween" season riding: fall and spring when the sun is low in the horizon. I also have the Sunblocker which is for summer use; keeps the "squint" out of your eye, but cannot compare to the effectiveness of the Supervisor.
Downside of the Supervisor, is that it boxes in your vertical vision. While the supervisor has detachable plastic tabs, they do break. I ended up drilling small holes in the top of my visor, and screwing in the Supervisor to a permanent fix.