furikake?

I would like to know more about furikake. Is it mixed with rice before moulding it into sushi shapes? is it sprinkled on moulded sushi? is it sprinkled on plain white rice before eating?

The last one is correct.
http://www.e-marujo.co.jp/cart/detail.asp?id=10&pid=2

It is never used to make sushi at least in Japan.

But when you make onigiri, it's all right to mix it with plain white rice before moulding.
http://www.koujuan.co.jp/recipe/2006/12/post_51.html

I imagine that when the original poster says "sushi," what he/she means is the rectangular-shaped molded rice, not really the dish sushi (with fish fillet on top) as we know it :)

"furikake" is normally sprinkled on cooked plain rice (served on a bowl), OR on top of moulded rice, and normally sprinkled right before you eat it. The name comes from the verb "furikakeru" meaning "to sprinkle, to shower (something on top of something)." So toppings, normally dry and different bits of ingredients mixed that you sprinkle onto rice to flavor it would be "furikake."


But of course since it is rice seasonings, if you want to, you can certainly season the rice first with it and THEN shape them into "onigiri"
(hand-shaped rice balls) or turn into moulded shapes as well.

I think they started as dry toppings to be sprinkled right before eating, so many are enjoyed relatively dry, immediately after sprinkling, so that you enjoy the crunchiness, and others that taste just as well even if you mix into the rice (moist and blended into the rice). Some manufacturers sell them under different names/series - they might call it "onigiri no moto," meaning "flavorings for onigiri (rice balls)."