I've just returned from a holiday in Iceland (I can heartily recommend it, BTW). I took a break from Stack Exchange as well, but I guess one can never stop being a moderator... I couldn't help but notice the Apple Command key symbol, the logo of our sister site Ask Different
being used on a couple of road signs, e.g. this one near the Háifoss waterfall:
The Ask Different logo is derived from the Command key – we can't use an Apple-like logo since we're "not affiliated with or endorsed by Apple Inc. in any way." (see our footer).
Sometimes, a modified version with a caret ('roof') is used:
I thought I found the answer on an information board just inside Hveragerði which says it's for Hot Spring Areas:
but that doesn't make sense; the Háifoss is 'just' a waterfall and the Ráðhús is a town hall.
Bonus question: is this something Iceland specific or is it used in other countries as well?