What we want but hasn't been invented yet!

[darrsi]

they might be better now but I tried one a few years ago and it just never got dark enough 

I have the clear one, and the tinted one which was certainly good enough in summer.
Apart from the anti fog properties I also like the fact that they get rid of headlight glare at night as well.

There's a bit of a knack to fitting them, because you need to get it right first time with the double sided tape, you can't just peel it off to readjust it.
And you need to have the visor totally clean, and dust, hair and shit free, otherwise you're doomed to have to stare at it.

I've got it down to a bit of an art now, and every 1 or 2 years i'll reapply and shape new double sided tape in one long length on my visor so that it stays air tight.
Because I ride all year round water will eventually find a way in, normally around the top somewhere, then it's time to change the tape again.
I use Sticky Stuff Remover to get the old gunk off, as it doesn't hurt anything.